I know the British had colonies in the Pacific such as Singapore, and the USSR took Manchuria and Korea, but how in involved were British and Soviet forces in the Pacific?
I have written some answers pertaining to the British involvement in the Pacific War. None of them are general in nature however. A good start, in my opinion, to learn about British involvement in the war against the Japanese is to learn about perhaps the most brilliant British general of WWII: Field Marshal William Slim.