In the Aleutian Islands, the Japanese garrison on Attu had been annihilated by invading U.S. forces in the Battle of Attu between 11 and 30 May 1943. On 21 May 1943, with the situation on Attu deteriorating, the Japanese Imperial General Headquarters decided to evacuate the isolated garrison on Kiska. The evacuation began by submarine on 26 May 1943. Submarine Division 7 was reassigned to the 5th Fleet on 1 July 1943, and on either 1 or 2 July "I-6" set out from Yokosuka on her sixth war patrol, bound for Paramushiro in the Kuril Islands. After calling at Paramushiro, she deployed to support the ongoing evacuation of Kiska, patrolling with "I-5" in the Bering Sea north-northeast of Kiska. Between 17 and 19 July 1943, the two submarines sighted three U.S. destroyers on three separate occasions, but were unable to attack them. The Japanese completed the evacuation on 28 July 1943, and "I-6" concluded her patrol with her arrival at Paramushiro on 4 August 1943.