What August 1945 battle — one of the last engagements of World War II — marked the start of the Soviet invasion of the Kuril Islands near Japan?

What August 1945 battle — one of the last engagements of World War II — marked the start of the Soviet invasion of the Kuril Islands near Japan?

Battle of Kwajalein
Battle of Mukden
Battle of Tsushima
Battle of Shumshu
Battle of Chemulpo Bay

The correct answer is Battle of Shumshu