The Japanese were not aware of the base's existence during the April 1942 carrier raids in the Indian Ocean, and Somerville's fleet used it extensively. Later in the war, submarine reconnaissance established the base's existence, but by this point the Imperial Navy had no designs for a large-scale offensive in the Indian Ocean. The German submarine U-183 did torpedo the tanker British Loyalty in March 1944, making an impressive long-range shot from outside the atoll through a gap in the anti-torpedo nets.