Plans for the defense of the Philippine Islands had been in existence for many years when General MacArthur returned to active duty. The latest revision of these plans, completed in April 1941 and called War Plan ORANGE-3 (WPO-3 ), was based on the joint Army-Navy ORANGE plan of 1938, one of the many “color” plans developed during the prewar years. Each color plan dealt with a different situation, ORANGE covering an emergency in which only the United States and Japan would be involved. In this sense, the plan was strategically unrealistic and completely outdated by 1941. Tactically, however, the plan was an excellent one and its provisions for defense were applicable under any local situation. (Unless otherwise noted, this section is based on the Philippine Department Plan ORANGE, 1940 Revision. (Short title: HPD WPO-3), AG 326. The author has also had the benefit of conversations with the Philippine Department Commander, General Grunert, with Generals Sutherland and Marshall, and with various division commanders and staff officers who participated in the planning and execution of the plan.)
In War Plan ORANGE it was assumed that the Japanese attack would come without a declaration of war and with less than forty-eight hours’ warning so that it would not be possible to provide reinforcements from the United States for some time. The defense would therefore have to be conducted entirely by the military and naval forces already in the Philippines, supported by such forces as were available locally. The last category included any organized elements of the Philippine Army which might be inducted into the service of the United States under the Tydings-McDuffie Act.
An analysis of Japanese capabilities, as of 1 July 1940, led the Philippine Department planners to believe that the enemy would send an expedition of about 100,000 men to capture Manila and its harbor defenses in order to occupy the Philippines, sever the American line of communications, and deny the United States a naval base in the Far East. It was expected that this operation would be undertaken with the greatest secrecy and that it would precede or coincide with a declaration of war. The garrison therefore could expect little or no warning. The attack would probably come during the dry season, shortly after the rice crop was harvested, in December or January.
The enemy was assumed to have extensive knowledge of the terrain and of American strength and dispositions, and would probably be assisted by the 30,000 Japanese in the Islands. Army planners in the Philippines expected the Japanese to make their major attack against the island of Luzon and to employ strong ground forces with heavy air and naval support. They would probably land in many places simultaneously in order to spread thin the defending forces and assure the success of at least one of the landings. Secondary landings or feints were also expected. It was considered possible that the Japanese might attempt in a surprise move to seize the harbor defenses with a small force at the opening of hostilities.
Enemy air operations would consist of long-range reconnaissance and bombardment, probably coming without warning and coordinated with the landings. The Japanese would probably also attempt to establish air bases on Luzon very early in the campaign in order to destroy American air power and bomb military installations.
Under WPO-3 the mission of the Philippine garrison was to hold the entrance to Manila Bay and deny its use to Japanese naval forces. There was no intention that American troops should fight anywhere but in central Luzon. U.S. Army forces, constituting the Initial Protective Force, had the main task of preventing enemy landings. Failing in this, they were to defeat those forces which succeeded in landing.
If, despite these attempts, the enemy proved successful, the Initial Protective Force was to engage in delaying action but not at the expense of the primary mission, the defense of Manila Bay. Every attempt was to be made to hold back the Japanese advance while withdrawing to the Bataan peninsula. Bataan was recognized as the key to the control of Manila Bay, and it was to be defended to the “last extremity.”
To reinforce the Initial Protective Force, Philippine Army units were to be mobilized immediately upon the outbreak of war and would be ready to participate in the defense of Bataan. If used as anticipated in WPO-3, which was prepared before July 1941, the Philippine Army would be under the command of the Philippine Department commander and would be utilized to defend Manila Bay. The plan did not contemplate using Philippine Army units for the defense of the entire archipelago.
WPO-3 divided Luzon, the principal theater of operations, into six sectors with a mobile reserve. Detailed plans for the defense of each sector were made by the sector commanders. The commander of the Philippine Division, the only U.S. Army division in the Philippines, in addition to conducting operations in the sector or sectors assigned to him, was to organize the defenses of Bataan and to command operations there if necessary.
Air support was to be provided by the 4th Composite Group, the predecessor of the Far East Air Force. This group was to obtain information of enemy location, strength, and . disposition by continuous reconnaissance, attack the Japanese whenever conditions were favorable, and support ground operations. In order to keep this air force in operation as long as possible, its planes were to be employed “conservatively” and every effort was to be made to supplement the strength of the group by taking over the Philippine Army Air Corps and commercial planes.
The navy was to set up defensive coastal areas at the entrances to Manila and Subic Bays. At the first sign of an attack a defensive area was to be set up around Manila to control all shipping and a patrol system established for Manila and Subic Bays. The Army, through the Department quartermaster, would control all shore facilities at the port of Manila.
The supply plan in WPO-3 was a complicated one. Provision had to be made to supply the six sectors during the initial phase of operations and to withdraw supplies into Bataan where a base would be established to support a prolonged defense. Supply officers estimated that they would probably require enough supplies for 31,000 men (the Bataan Defense Force )-later raised to 40,000 men-to last 180 days. The defense reserve already on hand, except for ammunition, was considered by the planners sufficient to supply such a force for the period required in a defensive situation.
The bulk of the supplies was stored in the Manila area which lacked adequate protection from attacking aircraft. In the event it became necessary to move the supplies to Corregidor and Bataan, the enemy would have to be delayed long enough to carry out this operation.
Prior to the start of operations on Bataan, supplies were to be moved rapidly to the peninsula. At the same time the Corregidor reserves, set first at a 6-month supply for 7,000 men and then for 10,000 men, were to be brought up to the authorized allotment. Philippine Department depots and installations in the Manila area were to be maintained just as long as the tactical situation permitted. Depots at Fort Stotsenburg, Fort William McKinley, Tarlac, San Fernando, Manila, and elsewhere would supply the various sectors. A Bataan Service Area was to be established, initially to assist in organizing the final defense positions and ultimately to supply the entire force after it had withdrawn to Bataan for the last stand. All stocks in the Department, except those of the Harbor Defenses of Manila and Subic Bays, would eventually be transferred to Bataan.
Plans for local procurement included the exploitation of the Manila area with its commercial warehouses, factories, and transportation facilities. Procurement districts, coinciding roughly with the sector boundaries, would be established later. Troops would take the field with two days of Class I supplies (rations), one emergency ration, and two days of fire. Class I and III supplies (gasoline and lubricants) would be issued automatically thereafter at rail or navigation heads; Class II, IV, and V supplies (clothing, construction and other heavy equipment, and ammunition) would be requisitioned from depots as needed. The issue of supplies to Philippine Army units would depend upon the speed with which they were mobilized ‘and their location.
The transportation of troops and equipment, the planners realized, would be a difficult problem. There was a large number of passenger buses on Luzon, centrally organized and operated. The 4,000 trucks on the island were of varying type, size, and condition and were mainly individually owned. Passenger buses were to be requisitioned immediately by the Army for use as personnel carriers. Since it would take longer to requisition trucks, cargo requirements were to be kept to an absolute minimum. In the initial move by the mobile forces toward the threatened beaches, little difficulty was expected with motor transportation. Later, as supply requirements rose and as troops moved back toward Bataan (if the enemy could not be repelled at the beaches), motor pools were to be formed. When Philippine Army units were mobilized the drain on the motor transport services was expected to increase greatly since these units had no organic motor transportation.
Nothing was said in WPO-3 about what was to happen after the defenses on Bataan crumbled. Presumably by that time, estimated at six months, the U.S. Pacific Fleet would have fought its way across the Pacific, won a victory over the Combined Fleet, and made secure the line of communications. The men and supplies collected on the west coast during that time would then begin to reach the Philippines in a steady stream. The Philippine garrison, thus reinforced, could then counterattack and drive the enemy into the sea.
Actually, no one in a position of authority at that time (April 1941 ) believed that anything like this would happen. Informed naval opinion estimated that it would require at least two years for the Pacific Fleet to fight its way across the Pacific. There was no plan to concentrate men and supplies on the west coast and no schedule for their movement to the Philippines. Army planners in early 1941 believed that at the end of six months, if not sooner, supplies would be exhausted and the garrison would go down in defeat. WPO-3 did not say this; instead it said nothing at all. And everyone hoped that when the time came something could be done, some plan improvised to relieve or rescue the men stranded 7,000 miles across the Pacific.
SOURCE: The Fall Of The Philippines by Louis Morton (United States Army Center of Military History)