The imperialist rivalry between Russia and Japan made war inevitable. Russia lost the war and under the Treaty of Portsmouth in 1905 Russia gave Japan the main railway through Manchuria, with adjoining territory. Thus, Manchuria became Japan's sphere of influence and was lost to the Manchus without their being consulted in any way. The Japanese penetration of Manchuria then proceeded stage by stage, not without occasional setbacks, until she had occupied the whole of Manchuria from 1932 to 1945. After the end of the second world war, Manchuria was returned to China, with certain reservations in favour of the Soviet Union, which were later revoked.