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(OTL) US Army Study: Invasions of Formosa (Taiwan) and Luzon

 
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mikey1983



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MessagePosté le: Lun Déc 26, 2022 00:24    Sujet du message: (OTL) US Army Study: Invasions of Formosa (Taiwan) and Luzon Répondre en citant

For reference. Hope I put this in the correct forum...


From "History of Planning Division, ASF" volume 5, parts 4 and 5 https://cgsc.contentdm.oclc.org/digital/collection/p4013coll8/id/1810/rec/4:

On 8 May 1944 (OTL), the US Army Service Forces (ASF) published a study on the feasibility of invading Formosa (Taiwan) in early 1945, with a view to bypassing Luzon and the central Philippines directly from New Guinea, the south sea islands, and Hawaii. In part 4 of the link, the ASF planners provide detailed estimates of the forces & shipping required, timetables, climatic conditions, Japanese capabilities, local infrastructure, and the viability of Formosa as a base for further operations against Japan, along with several maps. Continuing in the latter part of section 4 and into section 5 is an equally detailed prototype for the historical invasion of Luzon, published the same day. This continues into part 5, culminating in the third part of the study, "Comparison of the Logistic Feasibility of Operations against Luzon and Formosa" (the text is a bit thick but still legible). This last part is almost worth screenshotting verbatim, because it ruthlessly deconstructs any idea of a serious "debate" between the two alternatives: it was always going to be Luzon, politics or not, Mac or not; the ASF even goes so far as to question whether Formosa could have been invaded before the defeat of Germany freed up vital resources from Europe. This excerpt, as implied above, comes from Volume 5 of the "ASF" series, which runs from Volume I to Volume XI. All of them are free to download from CARL, and they could provide good reference material, if nothing else. Below is a (far from comprehensive) topics guide on this series:

    History of Planning Division, ASF topic guide

    Historical overview, table of contents: Table of contents

    European campaign, Persian Gulf command, CBI: vol. 1 part 3

    Pacific campaign: vol. 1 part 4
    Iwo Jima, Okinawa, Borneo, Downfall: vol. 1 part 5
    ^Volume 1 mostly deals with historical narratives while the other volumes are more nuts and bolts.

    General supply topics: vol. 2

    Seacoast defense, redeployment, demobilization: vol. 2 part 3

    American troops in CBI: vol. 3 part 1

    Logistical support for operation Rashness: vol. 3 part 2

    General operations against Japan (overview of possible 1944/45 operations): vol. 4 part 1

    Philippine staging area: vol. 5 part 1

    Formosa invasion (Operation Causeway): vol. 5 part 4

    Luzon invasion: vol. 5 part 4

    Logistical feasibility of Luzon vs. Formosa: vol. 5 part 5

    Honshu invasion: vol. 6 part 1

    Kyushu invasion: vol. 7 part 1, vol. 11 part 1

    Downfall in general: vol. 8 part 1

    Supplies worldwide: vol. 8 part 2

    Required forces against Japan/planned troop deployment worldwide: vol. 8 part 3

    Invasion of Germany from France: vol. 9 part 1

    Ammunition expenditures: vol. 9 part 3

    Future manpower and supply requirements (including Coronet strategic reserve, redeployment of forces, casualty planning): vol. 9 part 7.

    Historical demobilization planning (31 August 1945): Vol. 9 part 9

    Army-Navy supply conferences: vol. 10 part 1

    Kamchatka, Shumshu, Paramushiro operation: vol. 10 part 6



Below are the cliff notes versions of both invasion studies and the comparison of the two. For the full version, see the link at the top of this post.

Formosa invasion:



I. ASSUMPTIONS:

A. Target date is 15 February 1945

B. MINDANAO has been occupied, naval base and airfields have been established from which enemy sea and air capabilities in the PHILIPPINES have been so reduced so as to render them ineffective for interrupting the movement of allied troops and shipments.

C. The PALAUS have been occupied. Naval bases and airfields have been established. Naval and aircraft are operating against Japanese installations on LUZON and lines of communication in the CHINA SEA.

D. The European Axis has surrendered on 1 October 1944.

II. THE NATURE OF THE OPERATION (TAB A):

A. A carrier task force will attack by naval gunfire and air enemy installations on the Southwest Coast of FORMOSA in the vicinity of TAKAO [note: modern Kaohsiung, 高雄] and on the Northeast Coast near KEELUNG [Chinese: 基隆] on D minus 1.

B. On D day two amphibious assault divisions will land (ship to shore) to seize the port of TAKAO and the nearby airfields. At the same time two divisions will land to seize the port of KEELUNG.

C. About D+7 one follow-up division will land amphibiously ship to shore at TAKAO and two at KEELUNG. Three additional follow-up divisions will be landed about D+15.

D. On or about D+4 two assault brigades will land shore to shore on the PESCADORES.

E. Air and naval bases will be prepared for long range bombing of the Japanese mainland and for further operations against enemy forces in CHINA.

III. THE LOGISTIC PLAN TO SUPPORT THE OPERATION:

A. The two divisions assaulting TAKAO will be mounted in NEW GUINEA and will stage en route at DAVAO. The follow-up divisions will also be mounted in NEW GUINEA and will stage en route at DAVAO. The two divisions assaulting KEELUNG will be mounted in the RUSSELLS-GUADALCANAL. The two follow-up divisions will be mounted in HAWAII. The three additional divisions will be loaded in HAWAII.

B. All troops will be landed over beaches for the assault and initial build-up.

C. All initial and maintenance supplies will be landed over the beaches until such time as available ports can be secured and repaired to receive cargo ships. It is estimated that the major portion of supplies will be landed over the beaches for a period of at least 90 days (March, April, May). During July and August [1945] maintenance over beaches will be very limited due to typhoons, necessitating use of port facilities. Because of the NE monsoons, maintenance over beaches from September to February becomes increasingly more difficult.

D. Roads are readily accessible along most beaches. Capacity of roads is sufficient to clear the ports.

IV. CAPACITY OF LINES OF COMMUNICATION TO SUPPORT THE LOGISTICAL PLAN
[in link]

V. JAPANESE LOGISTIC PLAN TO OPPOSE THE OPERATION

A. The Japanese will have the use of existing port facilities, roads, and railroads. Early destruction of high trestle railroad bridges can seriously interfere with the use of railroad system.

B. Reinforcement in both troops and supplies will be by water and air from JAPAN and CHINA. Control of the Principal ports of KEELUNG (north coast) and TAKAO (southwest coast) by the United Nations would seriously interfere with logistical support of any large Japanese forces on the island.

VI. CAPACITY OF THE LINES OF COMMUNICATION TO SUPPORT THE JAPANESE LOGISTICAL PLAN:

A. Reinforcement capabilities:
Small groups by destroyer from HONGKONG: D+2-3
1/2 Division from CHINA or JAPAN: 5 days
2 Divisions from CHINA or JAPAN: 14 days
4 Divisions from CHINA or JAPAN: 30 days​

B. With the Japanese working on interior lines, the forces it is estimated they will have on FORMOSA can be supported by the existing road, rail, and port facilities. See section IV.

C. Control of the supply route from JAPAN to FORMOSA by the United Nations would seriously hamper the maintenance of the Japanese troops beyond existing stock piles. The latter it is expected will be of considerable quantity.

VII. TROOP BASIS

10 Inf Divisions (8 amphibiously trained)
10 AAA Gun Bns
10 AAA AW Bns, Mobile
5 Tank Bns
2 Cav Sq, Mechanized, Separate
4 Amph Tank Bns
12 Amph Tractor Bns
Other supporting Troops
Service Troops
25 Fighter and Medium Bomber Air Groups
15 VLR Bomber Groups

Total Forces:

    Ground Forces:
    10 Infantry Divisions at 15,000 each - 150,000
    Supporting Forces at 15,000 per division - 150,000
    Total - 300,000​

    Air Forces:*
    25 Tactical Air Groups at 5,000 each incl. Service Troops - 125,000
    15 VLR Bomber Groups at 5,000 each incl. Service Troops - 75,000
    Total - 200,000​

    Army Service Forces:
    10,000 troops per division - 100,000​

    Total Ground, Air, and Service Forces:
    600,000​

    *Eventual build up. 8 Tactical Air Groups will be moved in with assault and immediate follow-up forces​


VIII. SHIPPING CAPABILITIES TO SUPPORT THE PLAN:

A. The assault lift will require:
120 APA
40 AKA
7 AP (assault)
48 AK (assault)
200 LST
95 AP (follow-up)
95 AK (follow-up)

B. LST's are not suitable for this operation; therefore the assault must be made without the assistance of this type of craft. This condition may prejudice the success of the operation.

C. Shipping will be available within the theater without prejudice to other operations provided that the build up will extend over a period of 3-4 months with the garrison forces arriving in at least two separate increments. This impediment can be removed by employing a portion of the assault forces as garrison forces. 14,000 of the 144,000 follow-up strength will not be mounted in assault shipping but will be mounted in other shipping

IX. THE SUPPLY CAPABILITIES TO SUPPORT THE PLAN

Assuming that other demands for certain signal items and engineer work equipment can be deferred, if necessary, all requirements can be met.

X. CONCLUSION

The foregoing logistic plan is, from a mechanical standpoint, adequate to support the operation. From a practical logistic standpoint, assuming the operation is to be tactically sound, the plan is one of great hazard involving an extended line of communication for the assault and follow-up troops and their subsequent maintenance. The extreme distances from the staging and base areas require that the assault forces be mounted in APAs and AKAs. Although LSTs are capable of accomplishing the trip, their low speed of 8-9 knots, compared with the 15 knot normal capability of the fast convoys, would seriously prejudice the safety of the fleet, the convoy, and its immediate escort. A damaged vessel will be a loss, because when crippled it would be inexpedient to escort it back to a distant base. To convoy it will dissipate the strength of the escort assigned to the convoy, and the reduced speed would hazard the loss of the escorts for the individually convoyed ships. In addition an APA is capable of carrying only 26 LCVPs and 3 LCM (3)s. An AKA can carry 16 LCVPs and 8 LCM (3)s. LSTs would not be available. Therefore the assault against the formidable objective of FORMOSA would be mounted under serious handicap and might well prejudice the operation. A defeat would entail enormous losses which would be extremely expensive in personnel, materials, time, and the support of public confidence. A loss in the amount of 30 APAs and 12 AKAs would delay further operations in the Pacific a minimum of twelve months. The replacement of combat loaders is the criterion.

[Subsequent sections include Formosa's beach capacities, highways, special build projects, and the island's suitability as a base for future operations]
[Part II will be cliff notes for Luzon]
[Part III will be the pros and cons for each]
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patzekiller



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MessagePosté le: Lun Déc 26, 2022 07:01    Sujet du message: Répondre en citant

merci mickey, document trés interessant
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mikey1983



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MessagePosté le: Lun Déc 26, 2022 20:49    Sujet du message: Répondre en citant

Part 2: Luzon Invasion study, 8 May 1944



I. ASSUMPTIONS

A. Target date: 15 February 1945

B. MINDANAO has been occupied. Advanced naval bases have been prepared from which naval craft are operating against Japanese shipping to the PHILIPPINES. Airfields are in operation from which Japanese air capabilities on LUZON have been reduced to any except local effectiveness.

C. PALAU, YAP, and ULITHI have been occupied. Air and naval craft are operating against Japanese shipping and installations in LUZON, FORMOSA, and JAPAN. An advanced fleet base has been prepared in the PALAUS.

D. Forces based in MINDANAO have seized positions in southern MINDORO, PANAY, and NEGROS from which to control the SULU and CELEBES SEAS. PALAWAN, JOLO, and the CALAMIAN Group have been occupied.

E. GERMANY surrendered 1 October 1944

II. THE NATURE OF THE OPERATION (SEE TAB A)

Phase I - Intensive naval and air attack will begin on D-15 against selected targets to reduce the enemy's capabilities for resistance.

Phase II - By a combined amphibious ship-to-shore and airborne operation, landings will be made in ALBAY GROUP (LEGASPI) and SAN MIGUEL BAY in Southeastern LUZON. Fighter fields will be seized, port facilities acquired and passage through SAN BERNARDINO and BURIAS STRAITS secured.

Phase III - About D+3 a combined shore to shore and airborne assault will be made in TAYABAS and BATANGAS BAYS (Southern LUZON). These forces will advance eastward to join the force landed on D day in southeast LUZON, thence to the northwest on either side of LAGUNA de BAY to MANILA.

Phase IV - About D+10 a combined ship to shore and airborne attack will be made to effect a landing in LINGAYEN GULF. Subsidiary landings will be made at IBA or in DASOL BAY to seize airfields, intercept enemy reaction along the coastal highway and capture SUBIC BAY from the rear. The main forces will advance southward through Central LUZON, cooperating with the Southern LUZON forces in the capture of MANILA and the destruction of the Japanese forces.

At the earliest date after capture, naval facilities in MANILA will be restored, it will be prepared as a major mounting area, the airfields in LUZON will be restored and activated in preparations for further operations against FORMOSA, the CHINA Coast and the Japanese Mainland. It is considered that enemy resistance to the use of MANILA BAY will have been destroyed by D+30.

III. THE UNITED NATIONS' LOGISTIC PLAN TO SUPPORT THE OPERATION:

A. Forces will be mounted and staged as follows:

Two Infantry Divisions - Mount: NEW GUINEA - Stage: none
One Armored Division - Mount: U.S. - Stage: ENIWETOK

Two Infantry Divisions - Mount: RUSSELLS-GUADALCANAL - Stage: none
One Armored Division - Mount: U.S. - Stage: KWAJALEIN

Two Infantry Divisions - Mount: HAWAII - Stage: 1) YAP, 1) PALAU

Two and one-third Armored Divisions - Mount: U.S. - Stage: 1) GUAM, 1 and 1/3) ULITHI

One Airborne Division - Mount: NEW GUINEA - Stage: none*
Three Airborne Divisions - Mount: West Coast U.S. - Stage: none*
*Operational Base - MINDANAO

B. The assault forces will carry 5 days of supply of Classes I and III and 10 units of fire. Resupply will be from NEW GUINEA beginning on D+5 through LEGASPI, D+8 through BATANGAS BAY and D+15 through LINGAYEN GULF. Resupply from the UNITED STATES will begin on D+30.

C. Evacuation of wounded will be to GUADALCANAL and HAWAII

D. Port facilities at LEGASPI, BATANGAS, TAYABAS BAY and LINGAYEN BAY will be established by restoration of facilities and improvisation to the extent necessary to maintain the forces prior to the opening of MANILA (estimated at D+30).

E. The Forces landing in southern LUZON and those landing in TAYABAS and BATANGAS will operate as separate corps until a junction is effected. Thereupon they will be grouped into an army and a communications zone established. The forces landing in Lingayen GULF will operate as an army and will establish a communications zone. Army Group headquarters will be at DAVAO. The base areas will be considered to be the southern PHILIPPINES. Advanced bases will be established for the southern army at LEGASPI and BATANGAS and for the northern army at LEGASPI and SUBIC BAY. After capture, army group headquarters and bases will be established at MANILA.

F. Airfield facilities will be restored and created to accommodate 57 and 1/2 air groups.

G. MANILA harbor will be restored to the extent necessary to serve as a port of debarkation, a mounting area for five divisions and as a major naval base.

IV. THE CAPACITY OF THE LINES OF COMMUNICATION TO SUPPORT THE UNITED NATIONS' LOGISTIC PLAN:
[in link]

V. THE JAPANESE LOGISTIC PLAN TO OPPOSE THE OPERATION:

The Japanese can move reinforcements and supplies to the threatened areas by sea or air. It is believed, however, that a formidable United Nations' naval and air superiority at the time of these operations will seriously limit the logistical capabilities of the Japanese to build up troops and supplies after the assault.

VI. CAPACITY OF LINES OF COMMUNICATION TO SUPPORT THE JAPANESE LOGISTIC PLAN:

A. Reinforcement capabilities:

- Small force by destroyers from TAKAO: D+3
- 1 Division from TAKAO and HONGKONG: D+9
- 1 Division from SHANGHAI: D+12
- 1 Division from KOBE: D+15
- Additional Division each from:
--SHANGHAI: D+26-30
--KOBE: D+29-33

B. Military supplies on hand:

1. Munitions. The Japanese have very probably shipped in large surpluses of military supplies to bases in the vicinity of MANILA Bay areas - CAVITE, MANILA, CORREGIDOR, SUBIC Bay. Supplies shipped to ILOILO, CEBU, and DAVAO are believed to be rather meager - possibly only sufficient to provide for the needs of initial defense. Further supplies required could be shipped from FORMOSA. There is a possibility that supplies for DAVAO'S defense will be shipped from TRUK.

2. Fuel. It appears that the Japanese have concentrated most of their fuel supplies in the vicinity of MANILA Bay, CEBU City and DAVAO. Much of the storage is believed to be in drums rather than tanks. It is also believed that outside of MANILA Bay area fuel supplies are stocked in quantities only sufficient to meet initial defense requirements.

3. Transport. Mostly naval shipping is used by the Japanese in the Islands, there being very few merchant ships available. The only significant concentration of Japanese motorized transport appears to be around the MANILA Bay area, in the LUZON Plain and in the vicinity of LINGAYEN Gulf.

VII. TROOP BASIS

6 Infantry Divisions (amphibiously trained)
4 Airborne Divisions
4 and 1/3 Armored Divisions
7 Armored Amphibian Battalions
18 Amphibian Traction Battalions
12 AAA Gun Battalions
12 AAA AW Battalions, mobile
8 AAA AW Battalions, SP
4 Cavalry Squadrons, Mechanized, Separate
14 Tank Battalions

Other Supporting Forces
--Army Service Forces
52 Tactical Air Groups
--VLR Bomber Groups

Assault and Immediate follow-up:
6 Infantry Divisions - 144,000 men
4 and 1/3 Armored Divisions - 104,000 men
4 Airborne Divisions - 34,000 men
10 Air Groups - 50,000 men
Subtotal - 332,000

Garrison follow-up:
Ground Forces (balance of divisions above) - 165,300 men
42 Air Groups - 210,000 men
Total - 375,300

Grand Total - 707,300

VIII. SHIPPING CAPABILITIES TO SUPPORT THE PLAN:

A. Lift for the assault and immediate follow-up will require:
- 139 APA
- 50 AKA
- 240 LST
- 25 AP (follow-up)
- 64 AK (follow-up)
- 188 AP (garrison)
- 188 AK (garrison)

B. Shipping is available to move assault and immediate follow-up in appropriate type ships simultaneously. Troop and cargo lift for the garrison follow-up can be provided on the assumption that the build-up will extend over a period of 6 to 8 months.

IX. THE SUPPLY CAPABILITIES TO SUPPORT THE PLAN:

A. The requirement as a whole can be met in time. The following comment is pertinent:

1. The extent to which wire installations can be provided will depend on the extent of rehabilitation necessary. The tactical requirements can be met.

2. It is estimated that the port facilities at MANILA can be restored to an extent sufficient to mount 4-5 divisions in 120-150 days after occupation.

X. CONCLUSIONS:

A. The operation can be supported logistically.

B. A secure line of communications can be established for the support of operations against CHINA, FORMOSA, or JAPAN.

C. Naval bases, airfields, supply bases, and a 5 division mounting area can be established within 150-180 days after the occupation of MANILA.

[omitted from document: subsequent description of beaches, port capacity, road/rail, climate, etc.]
[Part III is the ASF's formal comparison of Luzon vs. Formosa]
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Archibald



Inscrit le: 04 Aoû 2007
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MessagePosté le: Mar Déc 27, 2022 09:37    Sujet du message: Répondre en citant

J'ai cette vision en tête d'un caporal chinois en train de lire ce fil et prendre des notes... on devrait peut être éviter de leur donner des idées, non ?
Laughing Laughing Laughing
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mikey1983



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MessagePosté le: Mar Déc 27, 2022 12:18    Sujet du message: Répondre en citant

Final part:

Comparison of the Logistic Feasibility of Operations against Luzon and Formosa (30 August 1944)

Items listed at left, 21 total, some omitted by me because typing them out would be monumental. Section 21 ("Conclusions") has a brief recapitulation of the major points covered.

1. BEACHES.
An examination of beaches indicates that they are adequate for full-scale operations thus far contemplated for either FORMOSA or LUZON.

2. PORTS.
LUZON
Port capacities are adequate to support air operations and maintenance of forces contemplated to garrison LUZON, and to mount approximately 5 divisions for subsequent operations. Capacity of selected ports on LUZON is as follows (in long tons, per 10 hour day. 1 long ton = 2,240 lbs = 1,016.047 kg)
- MANILA - 18,800
- CAVITE - 2,100
- OLONGAPO - 1,200
- PORO - 1,200
- MASINLOC - 900
- BATANGAS - 600
- Total 24,800 long tons/10 hour day or 744,000 LT/Month

FOMOSA
Port capacities are adequate to support either limited or expanded operations on FORMOSA and subsequent support of garrison forces and VLR operations therefrom, and mounting 5-7 divisions. The capacity of the main ports of FORMOSA is as follows (long tons/10 hour day)
- KEELUNG - 13,200
- GOSEI - 2,700
- TOSEKI - 4,800
- TAKAO - 12,000*
- Total 32,700 LT/10 hour day or 981,000/month
*Entrance to TAKAO being only 360 feet wide can be easily blocked by sinking a concrete laden ship (Liberty size) which it is estimated will take 10 days to two weeks to remove.

3. RESTORATION OF PORTS.
LUZON
SWPA has necessary units for necessary port construction and repair.

FORMOSA
CINCPOA will have to employ Navy CBs for port construction and repair. CINCPOA's plan for operation against FORMOSA makes the Navy responsible for port repair and restoration

4. ROAD CLEARANCES.
LUZON
Road capabilities of LUZON are adequate to clear all major and minor ports. An 8,000 ton capacity road extends northward from MANILA to LINGAYEN GULF area and a 4,000 ton road extends southeastward from MANILA. Central LUZON has an excellent network of roads feeding into or out of the main highways extending north and south from MANILA. Highways leading inland to MANILA from possible landing areas on central and southern LUZON provide much more capacity and freedom of movement for supply operation than FORMOSA.

FORMOSA
The road system of southern FORMOSA is considered adequate to clear the 12,000 ton capacity of the port of TAKAO locally. As operations extend northward the road capacities will be reduced to approximately 3,500 short tons per day which, it is estimated, will be adequate to support approximately 4 reinforced divisions. However, this will tax the road system extending north from TAKAO to the limit and will require rigid maintenance. Northward from TAKAO the road network on FORMOSA is limited to 2 main highways for the movement of troops and supplies. Flash floods cause the destruction of bridges during the monsoon season on the road system northeast of TOSEKI and south of KORYU. Locally the road clearance from KEELUNG, the major port of northern FORMOSA, is adequate. Operation in southern FORMOSA will involve crossing the very large SHIMO-TAMSUI River. In the vicinity of the main highway and railway bridges it is over one mile wide.

5. AIRFIELD CAPACITIES.
LUZON
Central LUZON has capacity for more airfields than will be required to support our contemplated air force deployment. It also has greater capacity than all of FORMOSA, particularly with respect to VLR fields. Airfield capacities of LUZON:

CENTRAL LUZON
VLR - 19
HB - X
MB - 3
FI - 3
Total - 25

ALL LUZON
VLR - 50
HB - X
MB - X
FI - 22
Total - 72
*HB and MB fields can be made available from fields not needed for VLRs

FORMOSA
An examination of the airfield capacities of FORMOSA indicated the following can be made available:

SOUTH FORMOSA
VLR - 3
HB - 3
MB - 5
FI - 6
Total - 17

ALL FORMOSA
VLR - 11
HB -11
MB - 10
FI -20
Total - 52

6. MOUNTING AND REHABILITATION AREAS.

LUZON
Mounting and rehabilitation areas for LUZON, located north and south of MANILA, to accommodate 5 divisions (60,000 men each). Time element for construction estimated at D+180. Development of LINGAYEN GULF area to necessary capacity would provide additional mounting capacity of 1 division.

FORMOSA
Mounting and rehabilitation areas for FORMOSA to accommodate 7 divisions, 2 south of TAKAO, 2 north of TAKAO, and 3 in the northern sector of FORMOSA. Time element for construction: 4 divisions capacity by D+175, 5 divisions capacity by D+220, 7 by D+250 if necessary.

7. SUPPLIES.
a. With the war continuing in EUROPE there will be a shortage of more major items such as 155 mm guns, heavy trucks 6-ton, steel treadway bridging, and transportation for this bridging. The SWPA is in a relatively better position with respect to heavy artillery than POA. Due to the higher priority theater ETO, there is a question as to whether any of these items can be furnished. Shortage of heavy artillery may eventually become a serious problem for the conduct of extended land operations which will occur in seizing such a place as FORMOSA.

b. Although medium and heavy ammunition is currently being rationed to the Fifth Army in ITALY in order to provide the necessary supply for the DRAGOON operation, it is estimated that the ammunition situation with respect to 155 how. and gun will be quite satisfactory for operation in either SWPA or POA based on the present stockage and allocations contemplated for the remainder of the year 1944, and the present expenditure rate. Eight inch (203mm) and 240mm ammunition in POA is not as satisfactory as SWPA. The present status of ammunition on hand and allocated to the end of 1944 is indicated for both SWPA and POA:

155mm gun
POA - authorized level: 198,000, on hand 176,000, allocated 56,000, total 232,000
SWPA - authorized level: 63,000, on hand 75,000, allocated 40,000, total 115,000

155mm howitzer
POA - authorized level 221,000, on hand 382,000, allocated 90,000, total 472,000
SWPA - authorized level 215,000, oh hand 282,000, allocated 211,000, total 493,000

8-inch howitzer
POA - authorized level 0, on hand 0, allocated 4,500, total 4,500
SWPA - authorized level 21,000, on hand 15,000, allocated 27,000, total 42,000

240mm howitzer
POA - authorized level 3,120, on hand 0, allocated 4,000, total 4,000
SWPA - authorized level 4,020, on hand 1,630, allocated 5,600, total 7,230

[...]

10. CARGO SHIPPING
If the European war continues into 1945 with ATLANTIC shipping demands proportional to present requirements, sufficient shipping can be made available to support SWPA operations through the central PHILPPINES and at the same time support limited CAUSEWAY [Formosa]. The PACIFIC situation will be such that deficits on the order of those presently being experienced will occur in 3 of the 5 months from September 1944 to January 1945, inclusive. From February 1945 onward, the PACIFIC shipping position will improve materially and will provide for replacement of reasonable losses incident to operations.

11. ASSAULT SHIPPING
[Excerpt only]
[...]
Above requirements for assault shipping are based on 12 APAs per division for the FORMOSA operation and 15 APAs for SWPA operations against LUZON. 12 APAs per division does not provide a sufficient reserve per division in case losses of any kind are incurred. Operating over extended lines of communication and against the Japanese homeland, FORMOSA must be so considered, strong reaction would be expected from the Japanese. A remark, very pertinent to this operation, contained in JPS 497/1 which gives an estimate of amphibious lift for PACIFIC operations, states "It is probable that Japanese reaction to an invasion of their homeland may be so violent as to require substantial reinforcement of our forces and in any case the requirements for replacements of both personnel and materiel are sure to be heavy." Reserves will not be readily at hand in case additional forces are required to make a successful lodgment on FORMOSA. Even though reserve forces might be available from SWPA in the central PHILIPPINES the time element for organizing a newly created reserve from this area and the time element of returning assault shipping from FORMOSA, if the assault shipping is available, will cause a considerable delay in getting the required reinforcements to FORMOSA. However, in case of a setback the Marine forces set up for operations against AMOY could be diverted to support operations on FORMOSA and a portion of that force could be diverted to seize PESCADORES which, though not as desirable as AMOY for a naval base, should be satisfactory.

12. BASES

LUZON
SWPA operations moving up through southern and central PHILIPPINES will provide a series of bases for our air forces to protect our lines of communication, and a position from which reserves can be safely moved to reinforce operations as it becomes necessary.

FORMOSA
In considering the support of operations against FORMOSA, CINCPOA will have to depend upon one main base, HAWAII, approximately 5000 miles distant, with a possible utilization of an intermediate base at GUAM. This means furnishing supplies and a movement of reserves over an extended line of communications subject to Japanese land based aircraft based on LUZON and Japanese submarines operating from bases either in LUZON or the RYUKYUS.

13. RESERVES

Recent operations in the MARIANAS have given a definite indication that an adequate reserve must be at hand to accomplish a successful assault and lodgment on any extensive land mass. On SAIPAN we suffered 17,000 casualties against an estimated force of 20,000. G-2 estimates indicate that by the time we conduct operations against FORMOSA the Japanese will have a combat force of approximately 150,000. If our casualties are as heavy in comparison as those on SAIPAN we will have a definite need for strong reinforcements which must be readily available. On the same basis as SAIPAN our casualties on FORMOSA would be approximately 125,000. Reserves for operations against LUZON [are] more readily available than for FORMOSA due to the shorter distances and less exposed line of communications.

14. LOCAL ASSISTANCE

LUZON
On LUZON considerable assistance can be expected from the organized guerrillas that are now in being. The constabulary force, though small, is well organized and can cause considerable disruption to the Japanese communications. Local assistance with respect to labor should be considerable.

FORMOSA
Of the total 6 million population on FORMOSA approximately 300,000 are Japanese, 150,000 Aborigines (head hunters), and the remainder Chinese-Formosan. Their attitude toward our forces will depend upon our initial success and a continuation of operations that will show the Chinese-Formosans that we definitely have the upper hand. Initially too much assistance cannot be expected either in disrupting Japanese lines of communication or rendering such labor assistance as we need in the conduct of supply operations.

15. SHIP-TO-SHORE VS SHORE-TO-SHORE OPERATIONS

LUZON
Both ship-to-shore and shore-to-shore operations will be conducted against LUZON.

FORMOSA
Operations against FORMOSA will necessarily have to be ship-to-shore because of the greater distances involved over seaborne lines of communication.

16. LAND-BASED AIR SUPPORT

LUZON
Operations against LUZON will have the advantage of land based air support established in the southern and central PHILIPPINES areas.

FORMOSA
Operations against FORMOSA will have to depend primarily upon carrier based aircraft for support. CINCPOA estimates that the air forces operating from southern and central PHILIPPINES can so continuously engage the enemy air forces on LUZON as to prevent its effective interference with POA operations against FORMOSA.

17. FLEET SUPPORT

During the period of landing operations against FORMOSA a large part of the fleet will of necessity be engaged in providing strong Navy artillery support and the necessary fleet escort for the carriers involved in giving direct air support to our forces not only during the critical period of landing operations but for an extended period of time which will be required for the seizure of sufficient land area in order to develop fighter fields for land based aircraft. Although we have the superior fleet this may not deter the Japanese fleet from attacking ours, either with small task forces or with a full Japanese fleet. The withdrawal of our supporting naval forces, all or in part, intentional or though force of circumstance, would leave our land forces in a very precarious position. POA forces are not too strongly equipped with respect to heavy artillery. An engagement with the Japanese fleet will at the same time involve withdrawal of carrier based air support from our land based operations. In operations against LUZON where we will be conducting both shore-to-shore and ship-to-shore operations, the withdrawal of fleet support in part or in full will not be as serious inasmuch as we will have land based air support for our landing and subsequent ground operations, particularly with our shore-to-shore operations. CINCPOA has previously commented on the fact that we should avoid dependence on carrier based aircraft for protracted land operations (CM-IM-2926). Operations against FORMOSA will involve protracted land operations. Without LUZON in our possession operations on FORMOSA must depend entirely on carrier based aircraft.

18. FUTURE ADVANCE FROM LUZON OR FORMOSA

a. The present strategy outlined in JCS 924 to attack JAPAN by way of FORMOSA-RYUKYUS-KYUSHU will find our forces attacking an ever-increasing strength of Japanese defenses involving extended operations, increasing losses not only to our forces involved in the land campaigns but to our naval forces required in direct support of those operations and the protection of our lines of communication. Such a definite line of advance will provide the Japanese with every opportunity for increasing the strengths of their positions. This coupled with an ever-increasing line of communications will increase the difficulties of our supply problems.

b. A direct advance against the Japanese homeland from a firmly established base such as LUZON will find the Japanese less prepared to meet our attack, particularly if they had been reinforcing their garrisons on FORMOSA and in the RYUKYUS, as has been indicated in the latest G-2 reports.

c. With a large operational air base on LUZON we will be able to effectively neutralize FORMOSA and portions of the RYUKYUS thus preventing their interference with our lines of communication to KYUSHU and at the same time we will be able to effectively cut their lines of communication through the CHINA SEA and to the DUTCH EAST INDIES, BORNEO, SUMATRA.

19. CAPACITY AS BASES FOR FUTURE OPERATIONS

LUZON
Mounting area for 5 divisions. Port capacities not as great as FORMOSA. Airfield capacity for strategic bombing greater than FORMOSA. Although Japanese shipping lanes south through CHINA SEA can be effectively bombed from LUZON, more effective work can be done from FORMOSA because of its better geographical position. Development of LINGAYEN GULF area would increase mounting capacity by an additional division.

FORMOSA
Mounting area for 7 divisions. Port capacities greater than LUZON. Although airfield capacities not as great as LUZON, FORMOSA can support contemplated deployment of 20 VLR groups. Closer to Japanese "Inner Zone" with resultant increase in effective bombing operations. Better position to cut Japanese lines of communication to SOUTH CHINA SEA, BORNEO, SUMATRA, MALAYA, etc.

20. GERMAN DEFEAT AND NO DEFEAT VS PACIFIC OPERATIONS

LUZON
Operations against LUZON can be conducted whether GERMANY is or is not defeated as the resources will be currently available for target date 15 February 1945 provided there is no concurrent operation against FORMOSA.

FORMOSA
With no defeat only limited operations can be conducted against FORMOSA due to lack of necessary forces to conduct a full-scale operation. Operations to capture all of FORMOSA must necessarily depend upon the defeat of GERMANY in order to provide the necessary forces and resources.

21. CONCLUSIONS

a. BEACHES
LUZON- Adequate
FORMOSA - Adequate for either limited or expanded operation

b. PORTS
LUZON - adequate. Capacity 24,800 LT/10 hr day or 744,000 LT/month
FORMOSA - Adequate. Capacity 32,700 LT/10 hr day or 981,000/month. Entrance to TAKAO port easily blocked. Time element to restore: 10 days to 2 weeks.

c. ROAD CLEARANCES
LUZON - Adequate capacity. Better network than FORMOSA
FORMOSA - Adequate local clearance from ports. North - south highways along west coast limited to 3,500 short tons per day or support of 4 reinforced divisions.

d. AIRFIELD CAPACITIES
LUZON - Adequate for contemplated operations. Greater capacity than all of FORMOSA. Central LUZON has capacity of 19 VLR fields and a total of 50 VLR fields for all of LUZON.
FORMOSA - Adequate for contemplated operations. Southern FORMOSA has capacity for approximately 4 VLR fields, all of FORMOSA capacity for 11 VLR fields

e. MOUNTING AREAS
LUZON - Capacity 5 divisions (60,000 men each). Time element for construction estimated at D+150
FORMOSA - Capacity 7 divisions. Time element for construction: 4 divisions capacity by D+175, 6 divisions by D+220, 7 divisions by D+250

f. SUPPLIES
LUZON - SWPA in a relatively better position with respect to heavy artillery than POA. SWPA in satisfactory position with regard to 155 how. and gun, and 8-inch and 240mm how. ammunition.
FORMOSA - shortage of heavy artillery may eventually become a serious problem. 155 how. and gun ammunition satisfactory in POA but very limited amount of 8-inch and 240mm ammunition available or allocated.

g. TACTICAL BRIDGING
LUZON - Secondary roads and bridging in LUZON will require more engineer effort than in FORMOSA due to large number of stream crossings. Overall tactical bridging requirements are relatively the same for LUZON as FORMOSA. LUZON will have more local material available than FORMOSA.
FORMOSA - Operations involve the crossing of the very large SHIMO-TAMSUI River in the vicinity of the main highway and railway bridges. Will require major bridge repairs and major bridging equipment.

h. CARGO SHIPPING
LUZON - With a German defeat or no German defeat adequate cargo shipping can be made available for operations against LUZON provided no concurrent FORMOSA operation is conducted. With a concurrent FORMOSA operation sufficient shipping can be made available to support SWPA operations through central PHILIPPINES.
FORMOSA - With no German defeat and the conduct of operations into the central PHILIPPINE area by SWPA forces adequate cargo shipping can be furnished for a limited operation against FORMOSA. With a German defeat full-scale operations against FORMOSA can be supported with the necessary cargo shipping.

i. ASSAULT SHIPPING
LUZON - With defeat or no defeat and no concurrent FORMOSA operation adequate assault shipping can be provided to support operations against LUZON including a necessary reserve.
FORMOSA - Sufficient assault shipping available for the limited operation based on 12 APAs per division which does not provide an adequate reserve

j. BASES
LUZON - SWPA operation will provide a series of bases in the advance towards LUZON. Land based air forces will be in a position to protect the lines of communication.
FORMOSA - Main base, HAWAII, approximately 5,000 miles distant, with an intermediate base at GUAM. Support must be rendered over extended and exposed line of communication.

k. LOCAL ASSISTANCE
LUZON - Organized guerrillas and constabulary force can render material assistance in disrupting Japanese communications. Considerable local labor will be available.
FORMOSA - Initially too much assistance cannot be expected from the very large Chinese-Formosan population on FORMOSA until we have shown that we hold the upper hand against the Japanese.

l. LAND BASED AIR SUPPORT
LUZON - Operations against LUZON can be conducted under land based air support established in southern and central PHILIPPINES.
FORMOSA - Operations against FORMOSA will have no land based air support but must depend primarily upon carrier based aircraft. Also dependent upon neutralization of hostile air on LUZON.

m. GERMAN DEFEAT VS NO DEFEAT
LUZON - Operations against LUZON are not dependent upon defeat of GERMANY.
FORMOSA - Full-scale operations against FORMOSA are dependent upon defeat of GERMANY. With no defeat a limited operation can be conducted against southern FORMOSA with SWPA forces neutralizing Japanese air on LUZON.

n. LUZON VS FORMOSA AS A BASE FOR FUTURE OPERATIONS:
1.) LUZON has greater airfield capacity.
LUZON has better road system to support land and air operations.
LUZON will provide more local support because of friendly populace.

2.) FORMOSA has greater mounting capacity (FORMOSA 7 divs, LUZON 5 divs).
FORMOSA more favorably located to cut Japanese L/C to south and closer to Japanese "Inner Zone" for bombing operations.

3.) Lines of communication to LUZON relatively secure.
Lines of communication to FORMOSA considered hazardous if LUZON in hands of Japanese.
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