NAVAL WAR COLLEGEMonterey Program

OPERATIONAL ART: APPROACHES TO MINDANAO IN WORLD WAR II

By

Ian S. Davis

Major, USA

A paper submitted to the Faculty of the Naval War College in partial satisfaction of the requirements of the Department of Joint Maritime Operations.

The contents of this paper reflect my own personal views and are not necessarily endorsed by the Naval War College or the Department of the Navy.

Signature: /s/ I. S. Davis . Ian S. Davis

Date: 09 NOV 2009

Signature: /s/ D. F. Overton D. F. OvertonAssociate Professor, JMO

Introduction

In May 1943, the Joint Chiefs gained approval from the Combined Allied Staff for a

course of action for offensive operations directed against Japan. After ruling out approaches the

Aleutians, Southeast Asia, or China, the Combined Chiefs approved the Joint Chiefs’ plan for the

Allied main effort to use the Pacific axis of advance. The plan centered on two approaches

within the Pacific axis that converged on the Philippine Islands. The main effort was the Central

Pacific approach. It was comprised of naval and amphibious ground forces under the command

of Admiral Chester W. Nimitz and traversed the Marshall Islands, the Caroline Islands, and the

Palau Islands to the Philippines. The supporting effort was the Southwestern Pacific approach,

commanded by General Douglas MacArthur. MacArthur’s approach concentrated on ground-

centric amphibious operations with naval and air support along the north coast of New Guinea,

through the islands between the Vogelkop Penninsula, to the Philippine island of Mindanao.

One year later, the Joint Chiefs issued an updated directive for the Pacific offensive. The

operational design for the Pacific offensive was based on analysis and operational design by the

Joint Chiefs, General MacArthur, Admiral Nimitz, and their staffs. Their coordinated planning

developed an operational design for the Allied offensive strategy in the Pacific Theater

synchronized two mutually-supporting lines of operation that focused on the establishment of a

foothold in the Philippines and ultimately the defeat of Japan. The resulting plan issued by the

Joint Chiefs in 1944 that employed both the Central Pacific approach and the Southwestern

approach plan was the optimal solution that met the desired objectives.1

This essay will use the operational factors to analyze the advantages and disadvantages of

the Central Pacific and Southwest Pacific approaches to the Philippines during World War II.2

1 This essay is based on the Joint Maritime Operations Fall Quarter 2010 Operational Art Examination prompt. The base reference is the issued monograph on the approach to the Philippines. See (Smith 1996).

2For further reading on the Operational Factors of Joint Operations, see (M. N. Vego 2007).

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Furthermore, application of the operational art and design by each of the commanders will show

how they exploited the advantages and mitigated the disadvantages of the operational factors as

they related to each of their approaches.3 Based on the analysis presented in the essay, the

conclusion will present a recommendation to the Joint Chiefs on their 1944 directive for action in

the Pacific.

Discussion

Admiral Nimitz and the Central Pacific Approach

The initial concept of the Central Pacific approach was based on pre-existing strategic

plans. In the eyes of the Joint Chiefs, the Central Pacific approach applied direct pressure to

Japan’s vulnerable eastern flank, disrupted Japanese maritime freedom of movement, and offered

direct access to the Japanese home islands. The approach also supported the plan for large-scale

bombing of the Japanese home islands by B-29 bombers. In total, the Central Pacific approach

focused not only on the intermediate objective of the Philippines, but ultimately on the ultimate

objective of the Japanese home islands.4

After receiving initial guidance from the Joint Chiefs’ concept in 1943, Admiral Nimitz

began his offense by seizing air and naval bases in the Gilbert Islands to set conditions for the

occupation of the Marshall Islands in early 1944. After a coordination meeting at Pearl Harbor

January 1944 and subsequent guidance in March 1944, he adjusted his initial plan. The Central

Pacific approach would invade the eastern and central Marshall Islands on February 1, 1944 and

the western Marshall Islands on April 15, 1944. Based on suspected weakness of Japanese

forces at Truk, Admiral Nimitz would bypass and use air power to neutralize Truk, Wolei, and

other enemy bases in the Carolines. The Marianas would be occupied by June 15, 1944 and the

3 For further reading on Operational Art and Design, see (United States Joint Chiefs of Staff 2008)4 (Smith 1996)

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Palaus starting September 15, 1944. This would secure a foothold in the Philippines and support

operations against Mindanao, Formosa, and the China coast.5

Based on the Joint Chiefs’ 1944 guidance, time became a critical operational factor to

Admiral Nimitz’ plan. Compared to the initial plan based on the 1943 guidance, the timeline

was greatly accelerated. In order to compensate for this shortened timeline, Admiral Nimitz

applied the principals of objective, mass, economy of force, and maneuver, along the Central

Pacific approach and selectively bypassed Japanese strongholds and neutralized them through

the application of air power. This allowed Admiral Nimitz to maintain the tempo of the offense

and sustain the initiative during the offense. By not getting mired in a sustained ground fight or

prolonged maritime engagements, forces can conserve resources for decisive engagements

against enemy decisive points. Conservation of men and equipment shortened the post-operation

refit increased the tempo, which subsequently unhinged the Japanese ability to reconstitute and

reorganize after an engagement. One salient disadvantage to the Central approach related to time

was the requirement to seize the Marianas. Although Admiral Nimitz and General MacArthur

recommended bypassing the islands, the Joint Chief directed their seizure to establish B-29

operating bases to strike the Japanese home islands.6

Due to the vastness of the Pacific Ocean and the great distance between the targeted

island chains, the Pacific naval forces enjoyed the advantage in terms of a large operational

space. This advantage allowed the force to maximize the principals of mass, maneuver, surprise,

and economy of force. The Joint Chiefs preferred the advantage of the Central Pacific approach

because it was shorter, more direct, and therefore less costly. Advanced technology allowed the

dispersion of forces and greater standoff from potential threats. The advantage of large

5 (Smith 1996)6 (Smith 1996)

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operational space along the Central Pacific approach contributed to the increase tempo of the

offense. The force used carrier based aircraft to maximize the operational reach within the space

and set the conditions for the close fight during decisive engagements. This allowed Admiral

Nimitz to apply echelons of fire throughout his battle space with organic fire support, from

maritime and aerial platforms. Another advantage of the Central Pacific approach in relation to

space was the establishment of B-29 operating areas in the Mariana Islands. With an operating

range of 5,830 miles, the B-29 could easily strike the Japanese home islands which were only

1,500 miles from Tokyo.7 The vast space favored Admiral Nimitz in terms in relation to the

over-extended Japanese lines of communication. The inability of the Japanese to resupply or

reinforce their elements at remote locations allowed Admiral Nimitz to bypass isolated packets

of resistance and penetrate lightly patrolled security screens. A disadvantage to the Central

Pacific approach was the extended logistic trains from ground-based depots.8

Admiral Nimitz’ 7th Fleet had an overwhelming force advantage over the Japanese

because of the depletion of the empire’s combat power, their over-extended lines of

communication and security screens, and their shortage of resources necessary to wage war. An

indicator of the diminishing Japanese combat power was found during the aerial attack of Truck

in February 1944. Because of the lack of Japanese resistance during the attack, the Allies

decided bypass Truk and neutralize it with air assets. This decision maintained the tempo of the

offense through that application of all of the principals of war. Superior leadership,

technological advances, and the rapidly increasing American naval power of the 7th Fleet favored

the Central Pacific approach and the rapid defeat of Japanese ground and naval forces. Admiral

Nimitz capitalized on his ability to maneuver and rapidly penetrate Japanese lines, effectively

7 (Boeing n.d.)8 (Smith 1996)

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cutting off forces from reinforcement. Applying the principal of economy of force, the main

effort forces could engage in decisive operations on Japanese centers of gravity and key terrain,

while supporting efforts could conduct shaping and security operations in support of the main

force. A force-related disadvantage for the Central Pacific approach was the Joint Chiefs’

directive to divide Admiral Nimitz’ Central Pacific force into two elements: one would continue

to the Philippines to meet with General MacArthur’s Southwestern forces, while the other

element would continue to the Marianas to apply direct pressure to the Japanese home islands.

While the splitting of the force supported the deception plan and shaped the battle space for the

seizure of the Philippines, it allocated combat power to the Marianas, which Admiral Nimitz did

not consider a necessary objective for his approach to the Philippines.9

General MacArthur and the Southwestern Approach

Since his departure from the Philippines in early 1942, General MacArthur was

determined to return to the islands to regain his command. After assuming command of the

Southwest Pacific Area, General MacArthur formulated his plan for retaking the Philippines.

His initial planning became the concept for what would become the Southwestern approach to

the Philippines. The concept consisted of a series of amphibious ground operations that began

on the north coast of New Guinea, continued northwest through the island chain, and established

a foothold in Mindanao. General MacArthur’s plan was focused on cutting the Japanese lines of

communication to the Indies. But, the arduous, slow-paced jungle fighting, vulnerability of the

force to Japanese land-based bombers, vast external support requirements, and inability to

disrupt Japanese freedom of movement in the Central Pacific made the Southwestern approach

the Joint Chiefs’ least-desirable course of action. In the eyes of the Joint Chiefs, General

MacArthur’s Southwestern approach lacked the desired tempo and was costly in terms of men

9 (Smith 1996)

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and resources and did not directly support their ultimate objective: the allied invasion of the

Japanese home islands.10

Based on the Joint Chiefs’ 1943 guidance, Generals MacArthur began his offensive to the

Philippines. At the time of the 1944 directive, he was executing the reduction of Rabual..The

latest guidance shortened the timeline with the directive to neutralize Kavieng and Rabual with

minimum forces and to speed the development of bases in the Admiralities. Southwestern forces

would seize Hollandia by April 15, 1944 to establish bases for striking the Palaus, western New

Guinea, and Halmahera. After establishing the bases, the Southwestern forces would conduct

decisive operations along the northern coast of New Guinea, Palaus, and Mindanao that

culminated with the projected 15 November landing in the Philippines.11

As the supporting effort, time was a critical operational factor and driving force for the

prosecution of the Southwestern approach. Thus, time was a disadvantage to the Southwestern

approach. In order to achieve mass at the Philippines and support the main effort in the Central

Pacific, General MacArthur was tied to a timetable driven by the pace Admiral Nimitz’ forces.

By applying the principals of mass, objective, economy of force, and simplicity at decisive

locations, the Southwestern element was able to maintain and steady tempo during the offense

and overcome this disadvantage. Some considerations that affected time were the estimated time

to drive Japanese forces to culmination during decisive operations, duration of post-operation

refit and reconstitution, maintaining the pace of success at intermediate objectives to meet the

Joint Chiefs’ timeline, and the pace of the main effort in Central Pacific.12

Due to General MacArthur’s strategic position in the in the Southwestern Pacific in 1943,

the factor of space was an initial advantage when the Joint Chiefs released their initial guidance.

10 (Smith 1996)11 (Smith 1996)12 (Smith 1996)

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Supported by bases in Australia, he had the advantage of short logistical trains and the ability to

project air power from land bases to support the defense and conduct shaping operations for the

offense. In addition to land-based assets, General McArthur also had naval assets to support

power projection and security during the offensive push from New Guinea to the Philippines. As

the Southwestern force distanced themselves from the Australian mainland, they became

vulnerable to Japanese forces located adjacent to the axis of advance. The offense along the

northern coast of New Guinea to the island of Vogelkop was not vulnerable Japanese forces in

the Marshall or Caroline Islands. To reinforce the advantage offer by distance, General

MacArthur’s flanks would receive protection from land-based airpower and organic naval assets.

Beyond Vogelkop, Southwestern forces were vulnerable Palau Islands on the right (north), and

the Netherland East Indies on the left (south). Organic, land-based air power would protect the

southern flank. Protection of the northern flank relied on the occupation of the Palau Islands by

Admiral Nimitz’ Central Pacific approach. As the Southwestern approach and Central Pacific

approach converged on the Philippines, the operational space became smaller and became more

contingent of the synchronization of the mutually supporting efforts to set condition for the

invasion of the Philippines. While there was greater mass at the decisive point (advantage),

freedom of movement and flexibility were reduced because of the reliance on the 7th Fleet to

shape the space in order to reach the decisive point (disadvantage).13

Because of General MacArthur’s prestige and prior experience in the Southwestern

Pacific area of operations, he held an intangible advantage as it applied to the factor of force.

His well-known determination to return to the Philippines defined a clear objective and unified

the command. Filipino resistance organizations strengthened their resolve to fight the Japanese

13 (Smith 1996)

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knowing that General MacArthur would fulfill his promise to return.14 Furthermore, his

perseverance to implement the Southwestern approach gained the support of the Australians who

had a vested interest in defeating Japanese forces that could directly affect Australia’s mainland.

Without their support, General MacArthur would lack essential combat power and support bases

to conduct his offense to the Philippines. Additionally, MacArthur’s prestige was an essential to

the deception plan for the Pacific axis of advance. The mutually supporting approaches of

General MacArthur and Admiral Nimitz hampered the Japanese that ability to identify the Allied

main effort and prevented massing of Japanese forces at the compromised decisive point- the

Philippine Islands. Another force advantage of the Southwestern forces was the experience of

the ground forces conducting amphibious operations. This experience allowed a shorter refit and

reconstitution time between operations and allowed General MacArthur to maintain the initiative

and tempo of the offense. The task organization of the force provided the ability to maneuver

and mass on key terrain to conduct decisive operations. General MacArthur exploited his

organic naval and ground-based assets to shape the battle space and protect his flanks. The

seizure of the Palaus by the Central Pacific approach protected the vulnerable northern flank as

the Southwestern approach closed on the Philippine coast and offset this force disadvantage. As

General MacArthur’s and Admiral Nimitz’ elements converged on the Philippines, their

combined relative combat power increased exponentially as the operational space was reduced to

a common decisive point.15

Conclusion

In conclusion, the Joint Chiefs’ 1944 directive that employed both the Central Pacific

approach and the Southwestern approach plan was the appropriate operational design plan to

14 (Morrison 1986)15 (Smith 1996)

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establish a foothold in the Philippines and set conditions to the defeat of Japan. The mutually

supporting approaches exploited the advantages and mitigated the disadvantages of the separate

lines of operation in relation to the operational factors of time, space, and force. Admiral

Nimitz’ Central Pacific approach maximized the direct route and tempo of the offense to rapidly

penetrate the Japanese perimeter, neutralize or bypass threat forces, and cut Japanese lines of

communication. The approach directly supported General MacArthur’s Southwestern approach

by protecting his northern flank by neutralizing the enemy threat in the Palaus. Although both

Admiral Nimitz and General MacArthur preferred to bypass the Marianas, the Joints Chiefs

decision to direct the Central Pacific force to size the Marianas and establish bases for B-29

attacks of the Japanese mainland was a sound and directly supported operational objectives.

General MacArthur’s simultaneously executed Southwestern approach leveraged its experienced

fighting force to systematically secure key terrain from New Guinea, cut the Japanese East Indies

lines of communication, and to poise for decisive operations in the Philippines. Furthermore, the

synchronized efforts along two lines of operation prevented the Japanese from massing on either

effort and masses overwhelming Allied combat power at the decisive point to seize the

Philippine Islands. Based on the analysis presented in this essay, I concur with the Joint Chiefs’

1944 directive for Pacific action during World War II..

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Bibliography

Boeing. History B-29 Superfortress. http://www.boeing.com/history/boeing/b29.html (accessed November 2, 2009).

Department of the Army. FM 3-0: Operations. Washington, DC: GPO, 2008.

Morrison, Samuel Eliot. History of United States Naval Operations in World War III: Leyte June 1944-January 1945. Vol. 12. New York, NY: Little, Brown, and Company, 1986.

Smith, Robert Ross. HyperWar: US Army in WWII: The Approach to the Philippines. United States Army Center for Military History. 1996. http://www.ibiblio.org/hyperwar/USA/USA-P-Approach/index.html#index (accessed October 28, 2009).

United States Joint Chiefs of Staff. Joint Publication 3-0: Joint Operations. Washington, DC: GPO, 2008.

Vego, Milan N. "Part III: Operational Factors." In Joint Operational Warfare: Theory and Practice, by Milan N. Vego. Rhode Island: Naval War College, 2007.

"The Factor of Time." In Joint Operational Warfare: Theory and Practice, by Milan Vego, III-19. Newport, Rhode Island: Naval War College, 2007.