Commonwealth Corps

The Commonwealth Corps was the name given to a proposed British Commonwealth army formation, which was scheduled to take part in the planned Allied invasion of Japan in during 1945 and 1946. The corps was never formed however, as the Japanese surrender obviated any need for it. Under the proposals the corps would have comprised Australian, British, Canadian and New Zealand forces.

By July 1945, United Kingdom leaders were proposing that five Commonwealth divisions be assembled in India, and that they be committed to the invasion of Japan from March 1946, a few months after the first planned landings by United States forces. The corps was to be accompanied by a 15-squadron tactical air force known as Tiger Force, consisting mostly of Royal Australian Air Force and Royal New Zealand Air Force squadrons. However, the Australian Advisory War Council did not endorse this plan, instead feeling that the Australia's heavy involvement in the Pacific War meant that Australian Army units should be involved in the initial landing, whilst it was also considering the attachment of units to US formations.

By the time of the Potsdam Conference however, General Douglas MacArthur&mdash;as commander of Allied land forces for the proposed invasion&mdash;was insisting that: the total Commonwealth land forces involved should be only three divisions; a combined Commonwealth corps should be formed and that it would operate as part of a US Army; it should use only US equipment and logistics; it should be kept in reserve rather than taking part in initial landings and; it should not include Indian Army units, due to "linguistic and administrative complications". Besides questions of American national prestige, which undoubtedly weighed heavily, behind these conditions was a desire to simplify the lines of communication and the logistic support arrangements of the invasion force. Indeed once established in Japan MacArthur intended to switch his strategic lines of communication direct to America.

On 8 August, the Chief of the Imperial General Staff, General Alan Brooke proposed that the corps comprise one Australian, one British and one Canadian division, as well as two New Zealand brigades. The corps was to be formed in the United States and train there for six months before deployment, and would have also been organised along the lines of a US corps and utilise American equipment. It is generally considered that the corps was to have included the British 3rd Infantry Division, and two new divisions being formed for the purpose of the invasion: the Australian 10th Infantry Division and the 6th Canadian Infantry Division.

British leaders were proposing that the corps be led by Lieutenant General Sir Charles Keightley, a British officer. The Australian government disagreed with the appointment of an officer with no experience fighting the Japanese however, and instead proposed Lieutenant General Sir Leslie Morshead for the command. Regardless the details of the corps' deployment were still being discussed when the war was ended by the atomic bombings of Hiroshima and Nagasaki. It seems clear, however, that the Commonwealth land forces would not have been used in the initial landings on Kyūshū under Operation Olympic. Instead they would most likely have been used during the landings on Honshū near Tokyo, scheduled to begin on 1 March 1946 under Operation Coronet, and which would have also included a French Corps. Regardless, some sources state that that MacArthur was proposing the further reduction of the Commonwealth land forces to an elite division. However, considering the likelihood of extremely high casualties in any such invasion, it must be considered likely that a much larger number of Commonwealth troops would have become involved following the landings.

Canadian
The Canadian Army Pacific Force was organized on the lines of a standard infantry division, with nine infantry battalions. However, to ease logistic concerns, U.S. military equipment was to be adopted, as well as U.S. Army organization. Therefore, three battalions were formed into "regiments" rather than brigades, and "cannon companies" were formed rather than anti-tank units. The battalions were named in Canadian fashion, rather than numbered, and the division was patterned after the 1st Canadian Infantry Division.