The Battle of Attu off the coast of Alaska involved which two nations?

The Battle of Attu, which took place from 11–30 May 1943, was a battle fought between forces of the United States, aided by Canadian reconnaissance and fighter-bomber support, and the Empire of Japan on Attu Island off the coast of the Territory of Alaska as part of the Aleutian Islands Campaign during the American Theater and the Pacific Theater and was the only land battle of World War II fought on incorporated territory of the United States. It is also the only land battle in which Japanese and American forces fought in Arctic conditions.

The more than two-week battle ended when most of the Japanese defenders were killed in brutal hand-to-hand combat after a final banzai charge broke through American lines.