Soviet invasion of South Sakhalin

The Soviet invasion of South Sakhalin, also known as the Battle of Sakhalin, was the Soviet invasion of the Japanese portion of Sakhalin Island also known as Karafuto Prefecture. The invasion was part of the Soviet–Japanese War, a minor campaign in the Asian theatre during World War II. == Background == Following the Japanese invasion of Sakhalin in 1905, control of the island was split according to the Treaty of Portsmouth, with the Russian Empire controlling the northern half and the Empire of Japan controlling the portion south of the 50th parallel north.

Source: Wikipedia — Soviet invasion of South Sakhalin (CC BY-SA 4.0)