In contrast to the large number of submarines which operated off the east coast, only a single Japanese submarine was dispatched against the Australian west coast. On 21 January 1943, left her base at Surabaya, East Java, destined for Western Australia. The submarine—under Lt. Cdr. Kennosuke Torisu—was tasked with creating a diversion to assist the evacuation of Japanese forces from Guadalcanal following their defeat there. Another submarine——had undertaken a diversionary bombardment of the Cocos (Keeling) Islands on 25 December 1942.