Battle Casualties and Medical Statistics

Effects of Type of Operation and Tactical Action

SOURCE AND LIMITATIONS

In war, battle casualties result from many complex factors which seldom,if ever, combine to produce identical situations for each type of campaign,each type of tactical operation, and, indeed, even for each type of tacticalaction. Some of these factors, which vary in significance, are the weaponsemployed and their relative firepower; the size and experience of opposingforces; the excellence of plan and tactics of battle; the type of terrainand advantage of position; and the tactical, strategic and logistical supportprovided. Disease cases, on the other hand, are more a product of exposurerelated to geography, climate, and season of year, while nonbattle injurycases result from external causes other than the hostile act of an enemy.The incidence of battle casualties, however, by particular operations andtactical actions, and of nonbattle admissions by type of operation, canoften provide a basis for the projection of the combined effects of certainof these variables, which are important from both the tactical and logisticalstandpoints. In addition, certain operations of the same type, by one coincidenceor another, produce battle casualty rates that are similar, and certaintypes of operations consistently average higher or lower battle casualtyrates than do other types. For example, certain types of ground operationsin World War II were observed to produce higher than average casualty rates(6). In preparing that material, research into division tacticsdid not go beyond the classification of ground operation for the entiredivision, and only counts of the wounded in action who lost time from dutywere made available.

The preparation of these data has included research into the tacticalaction of the separate regiments in relation to the type of ground operationof the division as a whole. Casualty counts for these operations have beenexpanded to represent the total number hit: the killed in action plus allof the wounded in action, even those who were slightly wounded and wholost no days from duty and were CRO cases.

The operations classified here account for 93 percent of the total numberhit (killed and wounded, including CRO cases) among U.S. Army troops inthe Korean War. Of the final medical counts, therefore, 18,654 of the 19,353killed in action, 72,926 of the 77,788 wounded-in-action admissions, and12,468 of the 14,575 slightly wounded CRO cases are included in the divisionaloperations. Detailed data for nonbattle as well its battle casualties areincluded in appendix B (source tables B-5 through B-11), separately, fordivisions, regiments, headquarters and service companies, division artillery,and for engineer, medical, and tank battalions, for every tactical divisionoperation of the Korean War.

The chief sources used in determining the types of tactical actionsand types of operations were the unit periodic operation reports, variousstaff journals, and other command and staff reports (7). These operationsreports were usually prepared each day and covered a unit's combat operationsfor the previous 24-hour period. No attempt was made to go below regimentsfor the tactical action, and, consequently, a few selected were necessarilyarbitrary, especially when more than one tactical action was given forthe three infantry battalions of a regiment. In general, the selectioninvolved nothing more than a determination as to which tactical action,on any particular day was most likely to have produced most, if not all,of the casualties in any single given regiment on the same day. Since reportingprocedure at Army and division level followed the pattern of recordingonly the principal tactical activity in which a particular regiment wasengaged in any 24-hour period, it was from these reports that final determinationwas made. The chronology of the various tactical operations, and the dateswhen U.S. Army divisions, their organic regiments, and attached separateregimental combat teams were committed or relieved, was documented moreaccurately and posed no special problems.

The classification of tactical operations was developed to classifyall of the killed and wounded-in-action casualties sustained by each ofthe eight

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Table 20.- Frequency distribution ofdivision periods, killed-in-action rates,¹ by type ofoperation

Killed in action per 1,000 men per day	Type of Operation
	Offensive operations	Pursuit operations	Maintain defensive lines	Limited operations from MBP2	Defensive operations	Withdrawal operations	Redeploy and regroup	Corps or Army reserve
0.0-0.19	14	10	43	8	1	5	2	8
0.2-0.39	17	1	1	8	7	1
0.4-0.59	6			9	5
0.6-0.79	1			5	4
0.8-0.99				4	3
1.0-1.19	1			3	2
1.2-1.39	2			6
1.4-1.59	2				1
1.6-1.79
1.8-1.99
2.0-2.19				1
2.2-2.39					1
2.4-2.59
2.6-2.79					1
2.8-2.99					1
3.0-3.19					1
3.2-3.39
3.4-3.59
3.6-3.79					1
3.8-3.99					1
Total	43	11	44	44	29	6	2	8
Mean, unweighted	0.39	0.11	0.06	0.62	1.10	0.12	0.04	0.003
Mean, weighted	0.36	0.14	0.05	0.63	1.18	0.10	0.05	0.01
Standard deviation	0.36	0.05	0.05	0.46	1.08	0.07	0.04	0.003

¹ Killed in action stated as number per 1,000average strength per day.
² Main Battle Position such as defensive lines.
³ Less than 0.005 per 1,000 men per day.

U.S. Army divisions and the two separate regimental combat teams whichserved at one time or another in the Korean War. The types of operationsand tactical actions reflect the character of U.S. Army divisional experiencein Korea, which is, to a certain extent, influenced by quality of the variousafter-action reports. The types of divisional operations developed areoffensive operations, pursuit and mopping-up, maintaining static defensivelines, limited operations from main battle positions, defensive (enemyoffensive) operations, withdrawal operations, redeploying and regrouping,and corps or army reserve. The types of regimental tactical actions areattack, heavy resistance; attack, light resistance; airdrop, attack; assaultriver crossing; defense, enemy attack or counterattack; withdrawal andrearguard action; patrolling; establish, hold, or consolidate defensivepositions; mopping-up or consolidating gains; movement or redeployment;and reserve.

The divisional operation covers an overall stated period of time andthe regimental action represents day-to-day tactical activity within theoverall divisional period. While most of these tactical actions pose nospecial problem of definition, some necessarily are slightly ambiguous.For example, "airdrop attack" includes not only the parachutedrop but also ground action of whatever classification that might occuron the same day. The action "establish, hold, or consolidate defensivepositions" includes the operation of outposts, security guarding,and, static defense on main battle positions, as well as the "holding"action on offense and defense. The only other less-well-defined actionis"patrolling," and that includes ambush, reconnaissance, security,contact, and raiding parties.

OFFENSIVE OPERATIONS

The major U.N. offensive operations in Korea occurred within the first16 months of the Korean War. These operations are distinguished from thelimited objective attacks by relatively small forces (limited operationsfrom main battle positions) in that each of the 11 offensives studied representsa major United Nations Forces effort against the enemy involving more thanone division over a wide front. In two instances, the experience of a singleU.S. Army division is shown. The first one (Inchon

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Table 21.- Frequency distribution ofdivision-periods, wounded-in-action rates,¹ by type ofoperation

Wounded in action per 1,000 men per day	Type of operation
	Offensive Operations	Pursuit operations	Maintain defensive lines	Limited operations from MBP	Defensive operations	Withdrawal operations	Redeploy and regroup	Corps or Army reserve
0.0-0.49	3	10	43	5		3	2	8
0.5-0.99	11		1	4	1	3
1.0-1.49	5	1		6	6
1.5-1.99	10			2	4
2.0-2.49	7			6	5
2.5-2.99	1			2	2
3.0-3.49	7			6	2
3.5-3.99				4	1
4.0-4.49				1	3
4.5-4.99	1			2
5.0-5.49	2			2	3
5.5-5.99				2
6.0-6.49
6.5-6.99	1			1	1
7.0-7.49	1			1
7.5-23.49
23.5-23.99					1
Total	43	11	44	44	29	6	2	8
Mean, unweighted	1.93	0.44	0.25	2.64	3.49	0.49	0.07	0.02
Mean, weighted	1.80	0.54	0.27	2.66	3.17	0.42	0.07	0.02
Standard deviation	1.57	0.33	0.11	1.87	4.08	0.27	0.02	0.01

¹ Wounded in action and admitted to a medicaltreatment facility, stated as admissions per 1,000 average strength perday.
² Main Battle Positions such as defensive lines.

landing) involved the 1st U.S. Marine Division and the 7th U.S. ArmyDivision; the second (Operations Nomad-Polar) involved a force of two Republicof Korea divisions along with the 24th U.S. Army Division, in both, dataare given for the respective U.S. Army division alone. Although these datacover only U.S. Army experience, every action included both Republic ofKorea and other United Nations Forces as well.

In these 11 offensive operations, six U.S. Army divisions and two separateregimental combat teams contributed 43 division-periods, averaging 14.7days and totaling 25,737 men hit. For all divisions, tables 20 and 21 givethe distribution of divisional KIA (killed in action) and WIA (woundedin action,) admission rates, respectively, expressed as cases per 1,000average divisional strength per day over the entire period of participationof each. These rates ranged from 0.02 to 1.45 for killed in action andfrom 0.17 to 7.40 for wounded in action. Frequency distributions for divisionalWIA-CRO rates are not shown because they represent neither unit lossesfor which replacements would be required nor admissions to medical treatmentfacilities from which hospitalization and evacuation requirements originate.Figure 4, however, presents the counterpart of these distributions forthe total hit, which includes the WIA-CRO cases.

The average divisional rates for major offensive operations as shownin table 22 are 0.36 KIA, 0.21 WIA-CRO, and 1.80 WIA-admissions for a totalof 2.37. These are weighted mean rates obtained by weighting each individualdivisional rate by the proportion of the total man-days for the specifiedtype of operation which it represents. The arithmetic means are slightlyhigher: 0.39, 0.25, and 1.93, respectively, totaling 2.57 hit per 1,000men each day. All of the rates given in table 22 are weighted mean rates,as they are in all of the succeeding tables. When statistical comparisonsare made on the total hit between different types of operations as wellas between operations of the same type, the differences are highly significant.However, the mean rates of certain pairs- for example, Operations Rippervs. Rugged; the Inchon landing vs. Operation Detonate; and the January1951 U.N. counteroffensive vs. Operation Dauntless- do not differ significantly(P>.05). Neither do the means differ for the two highest division rates,which represent the last two major offensives of the war and surpass allothers for any type of operation studied. This variation might indicatethat, while very different, rates are being averaged, nevertheless certaininstances do occur in which some uniformity exists. Table 23 presents weightedregimental rates per 1,000 men per day for the

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Figure 4.- Cumulative percentage distributionsof average U.S. Army divisional hit rates (KIA, WIA-CRO, and WIA admissions),by type of tactical operation, Korean War.

various regiment tactical actions performed during the parent divisions'offensive operations. Needless to say, these rates for each separate typeof action differ significantly between the several types of operationswith, but one exception. The mean hit rate of 11.13 for the airdrop attackof the 187th Airborne Regimental Combat Team at Munson-ni in support ofOperation Ripper (table 23) does not differ siguificantly from that (12.33)for the jumps on the Sukchon-Sunchon area north of Pyongyang to trap retreatingNorth Koreans during the Eighth U.S. Army's operations of pursuit (table24). However, if the relative distribution of killed and wounded is considered,a significantly higher pro-

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Table 22.- Killed and wounded in actionduring major offensive operations, U.S. Army divisions, Korean War

Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
					Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Breakout of Pusan Perimeter	16-27 Sept. 1950	4	48	15,217	4,334	790	340	3,204	5.94	1.08	0.47	4.39
Inchon Landing and Liberation of Seoul	18-30 Sept. 1950	1	13	14,127	418	94	5	319	2.28	0.51	0.03	1.74
Counteroffensive against Chinese Communist Forces	25 Jan.-20 Feb. 1951	6	125	16,495	3,788	667	218	2,903	1.84	0.32	0.11	1.41
Operation Killer- to reestablish UN Line east of Wonju	21 Feb.-7 Mar. 1951	4	56	16,135	1,065	144	11.7	804	1.18	0.16	0.13	0.89
Operation Ripper-to outflank Seoul and capture Chunchon	7 Mar.-4 Apr. 1951	6	161	16,562	3,786	506	329	2,891	1.41	0.21	0.12	1.08
Operation Rugged- to secure phase Line KANSAS	1-15 Apr. 1951	6	44	17,278	1,057	156	136	765	1.40	0.21	0.18	1.01
Operation Dauntless- to secure phase Line UTAH	10-22 Apr. 1951	3	36	18,479	1,151	95	73	983	1.73	0.14	0.11	1.48
Operation Detonate- to retake Line KANSAS after Chinese Communist Forces Spring Offensive	20 May-8 June 1951	6	88	19,201	3,725	530	376	2,819	2.20	0.31	0.22	1.67
Operation Piledriver- to secure Line WYOMING and Iron Triangle	3-12 June 1951	4	35	18,622	2,018	231	379	1,408	3.09	0.35	0.58	2.16
Operation Commando- to secure Line JAMESTOWN	3-15 Oct. 1951	2	16	19,942	2,643	405	230	2,008	8.28	1.27	0.72	6.29
Operation Nomad and Polar- to secure Lines later designated MISSOURI	3-15 Oct, 1951	1	10	21,585	1,752	265	76	1,411	8.12	1.23	0.35	6.54
Total		43	632	17,164	25,737	3,943	2,279	19,515	2.37	0.36	0.21	1.80

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

Table 23.- Killed and wounded in actionduring major offensive operations, by tactical action, U.S. Army regiments,Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, heavy resistance	18	208	3,290	12,596	1,800	678	10,118	18.41	2.63	0.99	14.79
Attack, light resistance	19	517	3,375	6,025	936	667	4,422	3.45	0.54	0.38	2.53
Airdrop attack, Munson-ni	1	1	4,223	47	3	0	44	11.13	0.71	--	10.42
Assault river crossing	15	39	3,071	1,182	179	118	885	9.87	1.49	0.99	7.39
Defense, enemy attack or counterattack	17	42	3,373	1,472	314	113	1,045	10.40	2.22	0.80	7.38
Patrolling	19	427	3,301	1,353	229	220	904	0.96	0.16	0.16	0.64
Establish, hold, or consolidate defensive positions	17	80	3,258	453	59	64	330	1.75	0.23	0.25	1.27
Mopping-up or consolidating gains	8	14	2,587	121	24	16	81	3.34	0.66	0.44	2.24
Movement or redeployment	19	164	3,295	298	35	50	213	0.54	0.06	0.09	0.39
Reserve	18	432	3,345	337	62	91	184	0.23	0.04	0.06	0.13
Total	151	1,924	3,319	23,884	3,641	2,017	18,226	3.74	0.57	0.32	2.85

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

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Table 24.- Killed and wounded in actionduring pursuit and mopping-up operations, by tactical action, U.S. Armyregiments, Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, heavy resistance	11	33	2,801	793	147	17	629	8.57	1.59	0.18	6.80
Attack, light resistance	14	69	2,953	197	42	7	148	0.97	0.21	0.03	0.73
Airdrop attack, Sukchon-Sunchon	1	2	3,407	84	37	0	47	12.33	5.43	--	6.90
Assault river crossing	2	6	2,851	65	11	1	53	3.80	0.64	0.06	3.10
Defense, enemy attack or counterattack	11	22	3,149	693	159	23	511	10.01	2.30	0.33	7.38
Withdrawal and rearguard	3	7	3,303	13	1	0	12	0.56	0.04	--	0.52
Patrolling	17	376	2,866	567	95	77	395	0.53	0.09	0.07	0.37
Establish, hold, or consolidate defensive positions	21	127	3,284	154	45	9	100	0.37	0.11	0.02	0.24
Mopping-up or consolidating gains	9	59	2,830	135	14	15	106	0.80	0.08	0.09	0.63
Movement or redeployment	19	123	3,014	119	26	4	89	0.32	0.07	0.01	0.24
Reserve	19	151	2,950	179	12	35	132	0.41	0.03	0.08	0.30
Total	127	975	2,965	2,999	589	188	2,222	1.04	0.20	0.07	0.77

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

portion of those hit at Sukchon-Sunchon were killed in action. As wasthe case with the divisional rates, certain pairs of regimental tacticalaction rates during divisional offensive operations are found to be similar;for example, attack light resistance, and mopping-up.

PURSUIT AND MOPPING-UP OPERATIONS

Operations of pursuit were easily defined and resulted from the completedisintegration of the North Korean Army in retreat. While the bulk of theirbattered army fled north, fragmented units cut off from escape formed pocketsof resistance in the hills of South Korea. Both of the areas north andsouth of the 38th Parallel required large sweeping actions in the pursuitand mopping-up of these enemy elements. The Iwon landing and pursuit bythe 7th U.S. Army Division, although a part of the general pursuit in NorthKorea, was considered separately to evaluate any differences that the amphibiouscharacter of this action may have produced. The three operations represent11 division-periods averaging 27.5 days in length. The distributions ofthe KIA and WIA admissions (tables 20 and 21) show a high concentrationbelow 0.20 and 0.50, respectively. The weighted mean rates for these operationsare given in table 25 and differ significantly. The pursuits in North Koreaagainst the main forces produced the highest rates. Since the landingson Iwon Beach and the movement north were virtually unopposed during thefirst few days, this latter operation resulted in relatively light casualties.The regiment tactical actions during division pursuit operations (table24) show that more, than one-half of the regimental-periods were spentin patrolling and establishing and holding defensive positions, the formerto locate the fleeing enemy and the latter to block his escape. All buttwo of the regimental rates for tactical actions in pursuit are lower thanthe corresponding regimental rates for division offensives: airdrop attack,as previously mentioned, and reserve status. The latter phenomenon resultedfrom the absence of any well-defined front, and units in reserve oftenfound themselves under attack from the bypassed enemy.

MAINTAINING STATIC DEFENSIVE LINES

The static type of defensive line in Korea developed from arbitraryphase lines which more often followed the natural features of terrain suchas river and ridge lines. These lines, delineated major objectives on offenseand composed secondary lines of resistance on defense. When it became apparentthat the thinly held line north of Seoul was disintegrating beneath theweight of a major Chinese Communist Offensive, U.N. Forces were orderedto withdraw, from North Korea to Line "D," beginning on 5 January1951. This line ran from the Yellow Sea in the west through Pyongtaek,northwest through Wonju and just north of Samchok on the east coast (fig.5). During most of this time, main Chinese Communist Forces pressure wason

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Figure 5.- Final demarcation line betweennorth and south Korea, 27 July 1953.

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Table 25.- Killed and wounded in actionduring pursuit and mopping-up operations, U.S. Army divisions, Korean War

Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
					Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Pursuit and mopping-up, south 38th Parallel	28 Sept.-30 Nov. 1950	5	113	16,946	832	194	129	509	0.44	0.10	0.07	0.27
Pursuit north of 38th Parallel to Yalu	5 Oct.-27 Nov. 1950	5	162	15,601	2,533	463	129	1,941	1.00	0.18	0.05	0.77
Iwon landing and pursuit, north 38th Parallel	31 Oct.-27 Nov. 1950	1	28	14,788	229	45	5	179	0.55	0.11	0.01	0.43
Total		11	303	16,028	3,594	702	263	2,629	0.73	0.14	0.05	0.54

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

Table 26.- Killed and wounded in actionduring operations maintaining static defensive lines, U.S. Army divisions,Korean War

Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
					Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Line "D" (Furthest Chinese Communist Forces penetration in South Korea)	5-29 Jan. 1951	6	107	16,548	372	93	13	266	0.21	0.05	0.01	0.15
Line BOSTON (South bank of Han River southeast of Seoul)	18 Feb.-6 Mar. 1951	2	32	16,194	147	22	26	99	0.28	0.04	0.05	0.19
Line KANSAS (Phase Line across Korea around 38th Parallel)	4-29 Apr. 1951	6	48	17,847	303	46	74	183	0.35	0.05	0.09	0.21
Line GOLDEN (Line halting Chinese Communist Forces Spring Offensive north of Seoul)	29 Apr.-19 May 1951	3	58	19,323	438	33	151	254	0.39	0.03	0.13	0.23
Line NO NAME (Line halting Chinese Communist Forces Spring Offensive north of Seoul)	29 Apr.-19 May 1951	3	55	18,486	223	27	18	178	0.23	0.03	0.02	0.18
Line WYOMING-I Corps (Phase Line forward of KANSAS around 38th Parallel on Western Front).	10 June-2 Oct. 1951	3	219	18,859	1,987	280	583	1,124	0.48	0.07	0.14	0.27
Line WYOMING-IX Corps (Phase Line forward of KANSAS above 38th Parallel on Central Front)	13 June-31 Oct. 1951	3	200	20,657	2,324	344	336	1,644	0.56	0.08	0.08	0.40
Line KANSAS/HAYS X Corps (Phase Lines above 38th Parallel in X Corps Sector on Eastern Front)	15 July-4 Oct. 1951	1	46	18,504	649	90	123	436	0.76	0.11	0.14	0.51
Line JAMESTOWN (Main Battle Position, Western Front)	7 Oct. 1951-27 July 1953	6	957	17,971	7,287	1,042	1,594	4,651	0.42	0.06	0.09	0.27
Line MISSOURI (Main Battle Position, Central Front)	23 Oct. 1951-27 July 1953	6	940	19,208	6,007	761	1,246	4,000	0.33	0.04	0.07	0.22
Line MINNESOTA (Main Battle Position, Eastern Front).	16 Oct. 1951-27 July 1953	5	832	19,808	6,990	891	1,385	4,714	0.42	0.05	0.08	0.29
Total		44	3,494	18,926	26,727	3,629	5,549	17,549	0.40	0.05	0.08	0.27

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

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Table 27.- Killed and wounded in actionduring operations maintaining static defensive lines, by tactical action,U.S. Army regiments, Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, heavy resistance	8	7	3,265	404	81	35	288	17.67	3.54	1.53	12.60
Attack, light resistance	20	53	3,427	688	100	64	524	3.78	0.55	0.35	2.88
Defense, enemy attack or counterattack	20	75	3,580	1,576	314	258	1,004	5.87	1.17	0.06	3.74
Withdrawal and rearguard	5	8	3,457	46	4	7	35	1.66	0.14	0.25	1.27
Patrolling	26	4,764	3,607	13,778	1,822	2,880	9,076	0.81	0.11	0.17	0.53
Establish, hold, or consolidate defensive positions	26	3,156	3,595	6,930	886	1,559	4,485	0.62	0.08	0.14	0.40
Movement or redeployment	26	421	3,609	391	66	75	250	0.25	0.04	0.05	0.16
Reserve	25	2,512	3,567	640	91	181	368	0.07	0.01	0.02	0.04
Total	156	10,996	3,593	24,453	3,364	5,059	16,030	0.63	0.09	0.13	0.41

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

Republic of Korea elements and the 7th U.S. Army Division from Wonjueastward to Checon. During the next 8 months, from February through September1951, other major lines, designated BOSTON, KANSAS, GOLDEN, NO NAME, WYOMINGand KANSAS/HAYS, reflected the main defensive positions of U.N. Forcesback and forth across the map of Korea. After the last major U.N. offensivesin October 1951, which advanced the U.N. Forces to more favorable terrain,the lines became more static and were supported by a series of strong outpostsforward of the main lines. The latter became known as the "OutpostLine of Resistance," and the main line was designated "Main.Battle Position." Attacks on single strong points, such as BloodyRidge, Heartbreak Ridge, Porkchop, and Old Baldy on the outpost lines,and other limited actions to move or improve positions on the main defensivelines, were omitted from operations in this class and placed in the classof limited operations from main battle positions. The last main battlepositions which remained more or less static to the end of the war in July1953 were Line JAMESTOWN on the western front, Line MISSOURI on the centralfront, and Line MINNESOTA on the eastern front. Figure 5 shows the finaldemarcation line as of 27 July 1953.

These operations (table 26) had the lowest rates of any active operation;only the passive operations of redeploying, regrouping, and reserve weresmaller. The distributions in tables 20 and 21 show the bulk of the ratesbelow 0.20 KIA and 0.50 WIA, respectively. The highest rate, 0.76 hit per1,000 men per day, occurred for the KANSAS/HAYS line in the X Corps sectorbecause most activity occurred there. Advances by X Corps tended to straightenand shorten U.N. lines, and in addition, this area was more remote fromthe Kaesong neutral zone. There are no large differences between the averagerates for the individual lines although the numbers are so large that anysmall differences in the rates are highly significant statistically. Thenumber with similar rates- for example, Line D and No Name; Kansas andMissouri; Golden, Jamestown, and Minnesota- indicate that one might findless variation in this type of operation. The static, nature of these operationsis also reflected in the fact that less than 1.5 percent of all of theregimental time was spent either in defending (defense and withdrawal actions)against enemy attacks on the main line or in counterattacking (attack actions)to restore positions (table 27). Almost three-fourths of the time was usedfor patrolling and holding the main positions, while the balance of timewas used for redeploying, regrouping, and reserve. The average daily regimentalrate of 0.63 hit per 1,000 was also the lowest rate experienced for anytype of active operation.

LIMITED OPERATIONS FROM MAIN BATTLE POSITIONS

Beginning in July 1951, with the start of peace talks at Kaesong onthe 38th Parallel, no large-scale operations were undertaken by U.N. Forcesthroughout the summer until October 1951. Limited operations, with relativelysmall forces of regimental size or smaller, were undertaken, however, tokeep the

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Table 28.- Killed and wounded in actionduring limited operations from main battle positions, U.S. Army divisions,Korean War

Limited Operations	Number of Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
						Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
WYOMING I Corps	6	1 July-3 Oct. 1951	6	20	19,280	1,134	166	192	776	2.94	0.43	0.50	2.01
WYOMING IX Corps	6	26 June-21 Sept. 1951	7	21	20,762	1,786	283	186	1,317	4.10	0.65	0.43	3.02
KANSAS X Corps	2	26 July-5 Sept. 1951	2	15	18,889	1,839	316	154	1,369	6.49	1.12	0.54	4.83
HAYS X Corps	4	9 Sept.-15 Oct. 1951	4	32	19,706	3,470	578	221	2,671	5.51	0.92	0.35	4.24
JAMESTOWN	16	16 Oct. 1951-24 July 1953	17	120	18,452	7,067	1,242	826	4,999	3.19	0.56	0.37	2.26
MISSOURI	4	10 Feb.-4 Nov. 1952	5	39	17,571	2,339	391	386	1,562	3.41	0.57	0.56	2.28
MINNESOTA	3	10 Feb.-4 Nov. 1952	3	10	20,851	307	57	49	201	1.47	0.27	0.24	0.96
Total			44	257	18,847	17,942	3,033	2,014	12,895	3.71	0.63	0.42	2.66

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

enemy off balance and to seize dominating terrain, thereby improvingthe defensive positions. On Line WYOMING in the I Corps area, (Westernfront) closest to the Kaesong neutral zone, the dominating terrain of theSobang Mountains was obtained in action during the first 4 days of July1951. Thereafter, activity was limited to raids and to two operations designedto sweep the enemy from the Corps front. On Line WYOMING, in the IX CorpsSector (Central front), several small-scale operations secured new positionson the line in addition to tank-infantry raids into the "Iron Triangle."Line KANSAS/HAYS in the X Corps sector (Eastern front) was furthest fromthe Kaesong neutral zone and a large portion of U.N. activity was centeredthere. The battles for Bloody Ridge from Line KANSAS sector of the lineand Heartbreak Ridge on the HAYS sector of the line are the most notableand were largely responsible for the high division hit rates of 6.49 and5.51, respectively, as given in table 28. When the rates are related tothe specific regiments of the U.S. Army 2d Infantry Division that foughtthere, very high regimental rates are obtained. The 9th Infantry Regimenton Bloody Ridge had average daily rates of 152 KIA, 201 WIA-CRO, and 16.49WIA-admissions, totaling 22.02 men hit per 1,000 troops exposed over a10-day period. The 23d Infantry Regiment fought for Heartbreak Ridge almosttwice as long as the 9th Infantry Regiment on Bloody Ridge, and sustainedaverage daily rates of 3.14 KIA, 0.30 WIA-CRO, and 11.48 WIA-admissions,totaling 14.92 men hit per 1,000.

Again, after the last two major U.N. offensives in October 1951, actionwas reduced from large military operations to company and platoon patrolsand raids. More often, the battles raged over single strong points or outpostsforward of the main lines which, themselves, remained more or less staticto the end of the war in July 1953. A total of 16 limited operations (seetables B-5 through B-11, appendix B) involved U.S. Army troops from LineJAMESTOWN, notably the several battles for outposts on Porkchop Hill andOld Baldy, and the defense of outposts Kelly, Carson, Elko, and Vegas,among others. The respective highest average, daily regi mental rates forany individual limited operation occurred on Line JAMESTOWN. The highestaverage daily regimental KIA rate appeared during the fourth battle forOld Baldy, 18-21, September 1952. The enemy first ejected the troops ofthe U.S. Army 2d Infantry Division from the peak. The 38th Infantry Regimentcounterattacked and, after a bitter engagement, reoccupied the position.The average daily regimental KIA rate for this regiment was 6.29; the WIA-CROrate, 1.44; and the daily WIA-admission rate, 17.44; totaling 25.17 menhit per 1,000 over the 4-day period. The 7-day attack of 24-30 October1951 on unnamed Hill 199 by the 5th and 7th Cavalry Regiments, U.S. Army1st Cavalry Division, produced the highest average daily regimental WIA-CROrate. This average rate was 6.58 WIA-CRO per 1,000 per day over the completeperiod and was experienced by the 5th Cavalry Regiment. Companion ratesfor this regiment were 2.63 KIA and 13.90 WIA-admissions,

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Table 29.- Killed and wounded in actionduring operations from main battle positions by tactical action, U.S. Armyregiments, Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, heavy resistance	17	92	3,602	7,883	1,223	630	6,030	23.79	3.69	1.90	18.20
Attack, light resistance	17	62	3,652	1,474	240	154	1,080	6.51	1.06	0.68	4.77
Defense, enemy attack or counterattack	20	101	3,609	5,221	1,054	550	3,617	14.32	2.89	1.51	9.92
Withdrawal and rearguard	3	3	3,496	10	2	4	4	0.95	0.19	0.38	0.38
Patrolling	23	183	3,598	1,223	149	299	775	1.86	0.23	0.45	1.18
Establish, hold, or consolidate defensive positions	21	190	3,591	958	196	150	612	1.41	0.29	0.22	0.90
Movement or redeployment	13	47	3,516	224	31	38	155	1.36	0.19	0.23	0.94
Reserve	17	103	3,542	87	6	38	43	0.24	0.02	0.10	0.12
Total	131	781	3,590	17,080	2,901	1,863	12,316	6.08	1.03	0.66	4.39

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

totaling 23.11 hit. The 7th Cavalry Regiment had much lower rates forall categories of casualty for a total of only 7.44 men hit per 1,000 perday. Both the highest average daily regimental WIA-admission rate and thehighest average daily regimental total hit rate occurred during the lastbattle for Porkchop Hill (6-10 July 1953), before the decision on 11 July1953 to abandon, the outpost since it had lost its tactical value. Elementsof the 17th and 32d Infantry Regiments, U.S. Army 7th Infantry Division,defended the position. The l7th Infantry Regiment through 10 July 1953,when it was relieved by the 32d Infantry, Regiment, sustained average dailyregimental rates of 26.66 WIA-admissions and 36.01 total hit, the highestof any individual limited operation. The average daily KIA rate was 4.93and the WIA-CRO rate was 4.42 per 1,000 per day for this regiment. The32d Infantry Regiment had slightly lower average rates in all categories,totaling 25.47 men hit.

Limited operations for U.S. Army troops from Line MISSOURI numberedonly four and, with one exception, (ambush operation), involved singlestrong points of unnamed Hills 598 and 391 and outposts Charlie and King.The attack on Hill 598 produced the highest average regimental rate forlimited operations from this sector of 16.66 total hit for the 32d InfantryRegiment, U.S. Army 7th Infantry Division, over a 14-day period in October1952. After the heavy battles in the X Corps zone on the Eastern front(later designated as Line MINNESOTA), the activity was relatively quietexcept for a couple flareups in the Heartbreak Ridge area. The highestaverage regimental rate for this sector, 12.49 total hit, was experiencedby the 27th Infantry Regiment, U.S. Army 25th Infantry Division, over anextremely short (2-day) period in September 1952. Operations of this typealso produced relatively high divisional rates and ranked second amongall types of operations in the Korean War. It is interesting to note, however,that the average divisional WIA-CRO rate of 0.42 topped all of the otherdivision WIA-CRO rates by type of operation. The weighted and unweightedmeans for division KIA and WIA-admissions, respectively, are almost identical(tables 20 and 21) and range, from 0.01 to 2.04 for KIA and from 0.05 to7.35 for WIA-admissions. A fairly even distribution throughout the rangeof values indicates less uniformity among operations of this type. Approximately70 percent (31) of the division KIA rates and about 61 percent (27) ofthe division WIA-admission rates exceeded 0.36 KIA and 1.80 WIA admissionswhich are the respective weighted mean division rates for offensive operations.Table 28 shows the average mean division rates for limited operations fromthe various lines with operations from Line KANSAS (largely Bloody Ridge)and from Line HAYS (largely Heartbreak Ridge) leading; operations fromLine WYOMING in IX Corps zone ranked third. Although specific operationsfrom Line JAMESTOWN produced individual high average regimental rates,the overall division averages ranked fifth. Table 29 gives the averageregimental rates for tactical actions performed during these limited operations.The regimental rates for attack, (against both heavy and light enemy resistance)are the highest experienced for any type of operation, as is the regimentalrate for movement and redeployment. This latter situation resulted fromthe difficulties

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Table 30.- Killed and wounded in actionduring defensive (enemy offensive) operations, U.S. Army divisions, KoreanWar

Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
					Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Delaying Invasion, South Korea	4 July-3 Aug. 1950	3	69	12,043	4,579	1,991	150	2,438	5.51	2.40	0.18	2.93
Defense of Pusan Perimeter	4 Aug.-15 Sept. 1950	4	168	14,345	11,431	2,623	717	8,091	4.75	1.09	0.30	3.36
CCF Counteroffensive, North Korea	25 Nov.-15 Dec. 1950	6	34	16,778	3,684	562	114	3,008	6.46	0.99	0.20	5.27
CCF Counterattack, Wonju-Chipyong Area	12-21 Feb. 1951	3	24	17,220	2,109	651	162	1,296	5.11	1.58	0.39	3.14
CCF First Spring Offensive, 1951	22-29 Apr. 1951	5	32	18,343	1,914	314	219	1,381	3.25	0.53	0.37	2.35
CCF Second Spring Offensive, 1951	17-22 May 1951	3	15	19,520	1,221	333	116	772	4.18	1.14	0.40	2.64
CCF Attack, Western and Central Front, 1952	6-13 Oct. 1952	1	8	17,395	399	51	119	229	2.88	0.37	0.86	1.65
CCF Attack ROK II Corps Front, 1953	10-18 June 1953	1	9	22,957	998	174	145	679	4.83	0.84	0.70	3.29
Battle of Kumsong River Salient	14-20 July 1953	3	17	21,860	900	182	137	581	2.42	0.49	0.37	1.56
Total		29	376	15,484	27,235	6,881	1,879	18,475	4.67	1.18	0.32	3.17

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

often encountered in attempting to reinforce or relieve troops on theoutpost line of resistance, especially when individual outposts were underattack by the enemy.

DEFENSIVE (ENEMY OFFENSIVE) OPERATIONS

During the first 11 months of the Korean War, North Korean and ChineseCommunist Armies launched six major offensives, beginning with the attackacross the 38th Parallel by the Russian-trained North Korean Army on 25June 1950. The seventh attack occurred in October 1952 and was the largestattack of the year. The last two enemy offensives occurred in June andJuly 1953 before the signing of the armistice agreement at Panmunjom. Theoperations in this class had the highest rates, on the average. The distributionsin tables 20 and 21 show about half of the division-periods centered between0.2 and 0.79 for KIA and between 1.0 and 2.49 for WIA-admissions. The weightedand unweighted averages differ by more than those for any other type ofoperation, and both are above the parallel rates for the other types. Theaverage WIA-admission rate of 3.17 compares with the corresponding divisionalWIA rate of 3.73 resulting from the major enemy counterattacks of WorldWar II (6). In both wars, these operations, coincidentally, averaged13 days in length. Table 30 presents the distributions of individual operations.The rates do not vary so widely as do the numbers hit. The highest divisionalrate, 6.46 bit per 1,000 per day, resulted from the Chinese Communist interventioninto the Korean War with their launching of a major offensive in November1950. The U.S. Army 2d Infantry Division met the full impact of the overwhelmingChinese Force and slowed the attack which might have endangered the EighthU.S. Army with envelopment. The U.S. Army 2d Infantry Division sustainedrates of 3.04 KIA, 1.28 WIA-CRO, and 23.50 WIA-admissions, totaling 27.82men hit per 1,000 per day over the period of this operation. Needless tosay, this was the highest hit rate for any U.S. Army division in the KoreanWar and the WIA-admission rate paralleled the average WIA rate of 23.30experienced during the beachhead landings on Saipan in World War II, thelatter being the second highest divisional WIA rate among all of the WorldWar II operations studied (6). The next highest individual divisionWIA-admission rate was 6.91 WIA per 1,000 per day, experienced by the U.S.Army 7th Division during the same defensive operation against the ChineseCom-

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Table 31.- Killed and wounded in actionduring defensive (enemy offensive) operations, by tactical action, U.S.Army regiments, Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, heavy resistance	16	70	2,767	3,234	638	126	2,470	16.69	3.29	0.65	12.75
Attack, light resistance	18	44	3,035	842	158	84	600	6.30	1.18	0.63	4.49
Defense, enemy attack or counterattack	21	350	2,639	14,076	4,038	782	9,256	15.24	4.37	0.85	10.02
Withdrawal and rearguard	18	91	3,246	1,602	306	67	1,229	5.43	1.04	0.23	4.16
Patrolling	20	189	2,514	1,159	232	121	806	2.44	0.49	0.25	1.70
Establish, hold, or consolidate defensive positions	24	253	2,924	2,144	440	279	1,425	2.90	0.59	0.38	1.93
Movement or redeployment	22	102	3,020	268	53	41	174	0.86	0.17	0.13	0.56
Reserve	21	134	2,774	226	37	37	152	0.61	0.10	0.10	0.41
Total	160	1,233	2,791	23,551	5,902	1,537	16,112	6.85	1.72	0.45	4.68

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

munists. There were two other defensive operations in the Korean Warwhen individual divisional KIA rates exceeded the rate of 3.04 for theChinese Communist Forces intervention. The highest KIA rate of 3.88 wassustained by the U.S. Army 24th Infantry Division when it was committedpiecemeal to help the Republic of Korea Army delay the invasion of SouthKorea. In fact, when all divisions are included, this latter defensiveoperation had the highest average division KIA rate (2.40 KIA per 1,000per day) of any operation regardless of type. The second highest dailyKIA rate for an individual division was 3.63 KIA per 1,000 experiencedby the U.S. Army 2d Division during the Chinese Communist Forces attackin the Wonju-Chipyong area in February 1951. The range of these individualrates is reflected in tables 20 and 21 and varies more widely than in anyother set of rates. Table 31 presents the details of each regimental tacticalaction during division defensive operations. More than one-half of allregiment days were spent in defensive, withdrawal, or holding actions,and the regimental rates for these actions are the highest for any operation.Patrolling during defensive operations also produced a higher regimentalrate than it did in any other operation, as did reserve status. Undoubtedly,the press of the enemy in this type of operation was responsible for theseresults.

WITHDRAWAL OPERATIONS

The two major withdrawal operations of the Korean War resulted fromthe Chinese Communist intervention, an action which resulted in the start,of a new war in Korea. The Eighth U.S. Army (less X Corps) ordered thewithdrawal of units overland through a succession of phase lines cul-

Table 32.- Killed and wounded in actionduring withdrawal operations, U.S. Army divisions, Korean War

Operations	Calendar period1	Number of divisions	Division days	Mean division strength	Number				Rate4
					Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Evacuation of Hungnam	1-24 Dec. 1950	2	43	15,044	638	117	13	508	0.99	0.18	0.02	0.79
Withdrawal from north Korea to Line "D"	2 Dec. 1950-16 Jan. 1951	4	151	15,843	1,157	193	192	772	0.48	0.08	0.08	0.32
Total		6	194	15,666	1,795	310	205	1,280	0.59	0.10	0.07	0.42

¹ Inclusive dates within which one or moreU.S. Army divisions (including attached separate Regimental Combat Teams)contributed combat days to the indicated operation.
² Slightly wounded-in-action cases treated on an outpatientbasis, usually at an aid station, and returned to duty before the closeof the morning report day.
³ Wounded-in-action and admitted to medical treatment facility.
⁴ Stated as cases per 1,000 men per day.

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Table 33.- Killed and wounded in actionduring withdrawal operations, by tactical action, U.S. Army regiments,Korean War

Tactical action	Number of regiments	Regiment days	Mean regiment strength	Number				Rate3
				Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Attack, light resistance	2	3	2,894	36	7	1	28	4.15	0.81	0.12	3.22
Defense, enemy attack or counterattack	5	11	2,870	179	45	18	116	5.67	1.43	0.57	3.67
Withdrawal and rearguard	12	76	2,704	743	155	18	570	3.61	0.75	0.09	2.77
Patrolling	16	95	2,916	116	15	9	92	0.41	0.05	0.03	0.33
Establish, hold, or consolidate defensive positions	16	127	3,025	181	24	4	153	0.47	0.06	0.01	0.40
Movement or redeployment	16	103	2,962	119	14	45	60	0.40	0.05	0.15	0.20
Reserve	12	195	2,977	119	7	70	42	0.20	0.01	0.12	0.07
Total	79	610	2,939	1,439	267	165	1,061	0.83	0.15	0.09	0.59

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

minating with line "D" below the 38th Parallel. The X Corps,on the other hand, withdrew its combat units to Hungnam on the east coast,where troops were evacuated over the beaches and returned to South Korea.The rates for these operations, given in table 32, are among the lowestfor any type of operation. The highest rate for an individual divisionduring withdrawal operations was sustained by the U.S. Army 7th InfantryDivision which was ordered to move from Chosin to the Hamhung-Hungnam areaand cover the withdrawal of all elements (Army-Marine-other U.N.) of XCorps. This resulted in 0.23 KIA, 0.01 WIA-CRO, and 0.99 WIA-admissions,totaling 1.23 hit per 1,000 each day. The U.S. Army 3d Infantry Divisionwas guarding the Hungnam perimeter and later relieved the 7th Divisionas the covering force. The 3d Division was also the last division evacuated.Its rates were slightly less: 0.15 KIA, 0.03 WIA-CRO, and 0.64 WIA-admissions,for a total of 0.82 hit per 1,000. When the distributions of those hitby type of operation are considered, the unweighted mean of 0.67 for withdrawaloperations does not differ significantly from that (0.60) for operationsof pursuit (P>.05). However, if weighted mean rates as shown in tables25 and 32 are compared and the contribution to chi square ignored for thosenot hit,* the difference is clearly outside the range of chance. Table33 gives the regimental rates, most of which are low compared with thosefor major operations of offense and defense. The regimental rate of 3.61hit for withdrawal and rearguard action, however, is the second highestrate for this type of action among all operations; only defensive (enemyoffensive) operations, with a regimental hit rate of 5.43 for withdrawaland rearguard action, was higher.

SUMMARY BY TYPE OF OPERATION AND TACTICAL ACTION

Although individual operations and tactical actions produce casualtyrates that are specific to a peculiar set of circumstances, nevertheless,certain operations of the same classification are found to be similar,as are certain of the tactical actions. In addition, the various classificationsserve to introduce some slight measure of uniformity for providing thebasis for projecting combined effects of certain of the inherent variables.Tables 34 and 35 summarize the U.S. Army division and regimental experienceby overall type of operations and type of tactical action, respectively.

It is to be expected that factors related to the tactics of operationsaffect battle casualty rates very markedly but produce relatively small,effects on rates of loss due to disease and nonbattle injuries. The frontispieceshows the disease and nonbattle injury admission rates compared with thekilled and wounded reflecting this phenomenon. Although the overall trendfor DNBI admissions is one of decline, the variations are most frequentlyobserved to be inverse to those of the killed and wounded.

Medical requirements for nonbattle patients

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* In this modification, the number of men who were notcasualties are excluded and only the measure of agreement between observedand expected numbers of casualties is calculated. The method used is amodified contingency-table approach, with the calculation of chi squareand its interpretation in the usual manner.

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Table 34.- Killed and wounded in action,by type of ground operation, U.S. Army divisions, Korean War

Type of operation	Number of operations	Number of division periods	Division days	Mean division strength	Number				Rate3
					Total hit	KIA	WIA CRO1	WIA Adm2	Total hit	KIA	WIA CRO1	WIA Adm2
Offensive Operations	11	43	632	17,164	25,737	3,943	2,279	19,515	2.37	0.36	0.21	1.80
Pursuit and mopping-up operations	3	11	303	16,028	3,594	702	263	2,629	0.73	0.14	0.05	0.54
Main static defense lines	11	44	3,494	18,926	26,727	3,629	5,549	17,549	0.40	0.05	0.08	0.27
Limited operations from defense lines	41	44	257	18,847	17,942	3,033	2,014	12,895	3.71	0.63	0.42	2.66
Defensive operations	9	29	376	15,484	27,235	6,881	1,879	18,475	4.67	1.18	0.32	3.17
Withdrawal operations	2	6	194	15,666	1,795	310	205	1,280	0.59	0.10	0.07	0.42
Redeploying and regrouping	1	2	32	15,397	62	26	3	33	0.13	0.05	0.01	0.07
Corps or Army Reserve	8	8	1,234	18,925	956	130	276	550	0.04	0.01	0.01	0.02
Total	86	187	6,522	18,305	104,048	18,654	12,468	72,926	0.87	0.16	0.10	0.61
Total (excluding redeploy- ment and reserve)	77	177	5,256	18,177	103,030	18,498	12,189	72,343	1.08	0.19	0.13	0.76

¹ Slightly wounded-in-action cases treatedon anoutpatient basis usually at an aid station, and returned to duty beforethe close of the morning report day.
² Wounded in action and admitted to a medical treatment facility.
³ Stated as cases per 1,000 men per day.

Table 35.- Killed and wounded in actionduring ground operations¹ by tactical actions, U.S. Army regiments,Korean War

Type of tactical action	Number of tactical actions	Number of regimental days	Mean strength	Number				Rate4
				Total hit	KIA	WIA CRO2	WIA Adm3	Total hit	KIA	WIA CRO2	WIA Adm3
Attack, heavy resistance	70	410	3,231	24,910	3,889	1,486	19,535	18.81	2.94	1.12	14.75
Attack, light resistance	90	748	3,341	9,262	1,483	977	6,802	3.70	0.59	0.39	2.72
Airdrop, attack	2	3	3,679	131	40	0	91	11.87	3.62	--	8.25
Assault river crossing	17	45	3,042	1,247	190	119	938	9.11	1.39	0.87	6.85
Defense, enemy attack or counterattack	94	601	2,994	23,217	5,924	1,744	15,549	12.90	3.29	0.97	8.64
Withdrawal and rearguard	41	185	3,039	2,414	468	96	1,850	4.29	0.83	1.17	3.29
Patrolling	121	6,034	3,494	18,196	2,542	3,606	12,048	0.86	0.12	0.17	0.57
Establish, hold, or consolidate defensive positions	125	3,933	3,576	10,820	1,650	2,065	7,105	0.78	0.12	0.15	0.51
Mopping-up or consolidating gains	17	73	2,783	256	38	31	187	1.26	0.19	0.15	0.92
Movement or redeployment	115	960	3,343	1,419	225	253	941	0.44	0.07	0.08	0.29
Reserve	112	3,527	3,450	1,588	215	452	921	0.14	0.02	0.04	0.08
Total	804	16,519	3,440	93,460	16,664	10,829	65,967	1.64	0.29	0.19	1.16
Total (excluding regiment redeployment and reserve)	577	12,032	3,445	90,453	16,224	10,124	64,105	2.18	0.39	0.24	1.55

¹Excludes division redeploying, regroupingand reserve periods of operation.
²Slightly wounded-in-action cases treated on anoutpatient basisusually at an aid station, and returned to duty before the close of themorning report day.
³Wounded in action and admitted to a medical treatment facility.
⁴Stated as cases per 1,000 men per day.

Table 36.- Admission rates, by type,U.S. Army division and separate regimental combat teams, U.S. Army, Korea,1950-53

Type of operation	All causes	Wounded in action	Disease and nonbattle injury
			Total	Disease	Nonbattle injury
Offensive	4.04	1.80	2.24	1.67	0.57
Pursuit and mopping-up	2.28	0.54	1.74	1.27	0.47
Maintain static lines	1.49	0.27	1.22	0.94	0.28
Limited operations from defense lines	4.12	2.66	1.46	1.15	0.31
Defensive	5.91	3.17	2.74	2.07	0.67
Withdrawal	3.25	0.42	2.84	1.59	1.24
Redeploying and regrouping	2.97	0.07	2.90	2.25	0.65
Corps or Army reserve	1.19	0.02	1.17	0.95	0.22

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34

Table 37.- Disease and nonbattle injury,¹bytype of ground operations, U.S. Army divisions, Korean War

Type of operation	Number of operations	Number of division periods	Division days	Mean division strength	Number			Rate2
					Total disease and nonbattle injury	Disease	Nonbattle injury	Total disease and nonbattle injury	Disease	Nonbattle injury
Offensive Operations	11	43	632	17,164	24,265	18,105	6,160	2.24	1.67	0.57
Pursuit and mopping-up operations	3	11	303	16,028	8,450	6,175	2,275	1.74	1.27	0.47
Maintain static, defensive lines	11	44	3,494	18,926	80,925	62,255	18,670	1.22	0.94	0.28
Limited operations from defensive lines	41	44	257	18,847	7,090	5,590	1,500	1.46	1.15	0.31
Defensive operations	9	29	376	15,484	15,930	12,045	3,885	2.74	2.07	0.67
Withdrawal operations	2	6	194	15,666	8,615	4,845	3,770	2.83	1.59	1.24
Redeploying and regrouping	1	2	32	15,397	1,430	1,110	320	2.90	2.25	0.65
Corps or Army Reserve	8	8	1,234	18,925	27,990	22,950	5,040	1.20	0.98	0.22
Total	86	187	6,522	18,305	174,695	133,075	41,620	1.47	1.12	0.35
Total (excluding Redeployment and Reserve)	77	177	5,256	18,177	145,275	109,015	36,260	1.52	1.14	0.38

¹Admissions to medical treatment facilities.
²Stated as admissions per 1,000 men per day.

cannot be expected to diminish in any proportiona1 relationship to thelull in battle. In planning for medical support of combat operations, accountmust be taken of requirements for the care of all patients and it mustbe recognized that the conditions (weather, terrain, sanitation, discipline,and extreme mental and physical stress) encountered in a specified operationdirectly affect the rates at which personnel require medical care for "nonbattle"causes. Table 36 gives the rates of admission in each type of operationconsidered for disease and nonbattle injury patients as well as for thosewounded in action. Additional data pertaining to disease and nonbattleinjury rates are displayed in table 37 and in the source tables includedin appendix B. Disease and nonbattle injury rates are not affected by tacticaloperations to anywhere near the same degree as are casualty rates. Somedifferences do exist, however, and are reflected more by the nonbattleinjury rate than by the disease rate, since fewer factors are involvedin their production. It should be evident, however, that combat operationstend to expose the individual soldier to conditions of disease in certainareas, to unfavorable climates and weather, to poor sanitation, and toextreme mental and physical stress. Those factors, related to combat, intensifythe exposure rate and thereby directly affect the magnitude of the diseaserate. It is apparent, therefore, that many factors must be considered inaddition to the average rate for both battle casualties and nonbattle losses.The U.S. Army experience of average rates for the Korean War representsonly base points or models for combat operations and tactical actions,for which the planner must adjust to meet specific sets of circumstances.