During the month of September 1941, the United States began to send additional armaments and troops to the Philippine Islands. Just a week prior to the attack there were only 31,095 American troops available for combat
which included approximately 12, 000 well trained Philippine Scouts and 5,609 Air Corps personnel.
31st Infantry Reg 1,750 Troops
4th Marine Reg 1,431 Troops
Philippine Scouts 12,000 Troops
200th CA-AA
1,767 Troops
803rd Engineers
451 Troops
194th Tank Battalion 424 Troops
192nd Tank Batallion 538 Troops
17th Ordnance 155 Troops
United States Navy Asiatic Fleet Under The Command Of Admiral Thomas C. Hart
Although the United States had maintained military forces, including a suabstantial number of indigenous units, in the Philippines since their annexation in 1898, the islands were largely unprepared for hostilities with Japan. This unpreparedness was the result of several factors . As a signatory of the Washington Naval Treaty in 1922, the United States had agreed, in exchange for limitations onJapanese shipbuilding, to halt construction of any new fortifications in the Pacific possessions. For the Philippines this meant that only the islands near the entrance to Manila Bay, particularly Corregidor were well protected. Similarly, the act to grant the Philippines commonwealth status in 1936, with independence scheduled for 1946--meant that the defense of the islands had to rely on the Philippine government, despite its limited resources. Reflecting these realities, the U.S. Joint Army and Navy Basic War Plan ORANGE, last updated in April 1941, limited defense of the islands to Manila Bay and critical adjacent areas. If attacked, the U.S. Army garrison was expected to withdraw to the Bataan Peninsula, a tongue of land on Luzon forming the northeastern boundry of ManilaBay, and to the island of Corregidor.The plan did not envision reinforcement or relief of the Philippine garrison. With a small Army committed to continental defense and a general agreement that in the event America went to war it would adopt a defeat Germany first strategy, the U.S. Military had reluctantly concluded that the Philippines MUST BE SACRIFICED IF THE JAPANESE ATTACKED.
REPORT ON THE PHILIPPINE CAMPAIGN PREPARED BY JENNIFER BAILEY FOR SECRETARY OF ARMY J. W. STONE
U.S.S. Houston
U.S.S. Peary
U.S.S. William B. Preston
  1. S.S. Canopus
U.S.S. John D. Ford
U.S.S. John D. Edwards