The Aparri Operation – The AIF plan for the invasion of Luzon 1944-1945

During 1943 Australian forces made their most significant contribution to the war in the Pacific. The ‘Reconquest’ operations in New Guinea were the largest ever Australian military operations. Some twenty-five Australian infantry battalions participated in these operations, the most to see action simultaneously since the battle in the Somme Valley in 1918, and they were provided with naval, logistic and air support that was immensely greater than anything provided to Australians during the First World War. Following these highly successful operations US forces in the South West Pacific Area (SWPA) took over major operations against the Japanese, while the Australian forces were either used to garrison New Guinea and the surrounding islands or withdraw to rest and retain for further operations. As the battlelines in the SWPA moved closer to the Philippines the Australian government provided General Douglas MacArthur with the I Australian Corps to use in his offensive. MacArthur’s initial planning for the invasion of the main Philippine island of Luzon called for this corps to play a critical role in the campaign through a landing at Aparri to establish an airfield and to drive on the central highlands on the island. Despite the initial planning in which this operation was to play a vital role in the overall the reconquest of Luzon, it was never carried out. Instead of being involved in the major offensive in the Philippines campaign the I Australian Corps was shunted off to invade the strategically insignificant region of Borneo in operations that would have no bearing on the outcome of the war. The landing at Aparri represented the only significant opportunity for Australian troops to once again be at the forefront of operations in the Pacific. This paper will assess the viability of the Aparri operation and detail the complicated strategic and political reasons why it was not carried out. It will argue that this operation would have made a major contribution to the Allied victory in the Philippines and that while the reasons for its cancellation may have been valid in the eyes of MacArthur’s planning staff they represented a major failing in intelligence operations in the SWPA