The corps ceased to exist in June 1944 when it was converted back into Western Command, which remained until the end of the war in 1945.

In the early stages of the command's existence, there were few troops to spare, as most of the defensive forces from the Militia were deployed along the eastern coast of Australia.

[4] Shortly after its establishment, III Corps was placed under the command of the South West Pacific Area.

[7] By this time, though, the threat of invasion had diminished and after this the corps was progressively drawn down, with the 6th and 13th Infantry Brigades being transferred out in January and February 1943.

As the tide of war against Japan turned in favour of the Allies, the role of 3rd Corps in defence of WA diminished.

[8]The main function of the corps then became the preparation of smaller units for active service in New Guinea and elsewhere in the Pacific.

[10] The corps commander, Bennett, retired in May 1944;[3] around the same time, the Australian government had decided to reduce the size of the Army.

In June 1944, the corps was re-designated as Western Command, and assumed the role of the previously existing line of communications area that had been established in the state earlier in the war.