and ; pleasure launches converted to channel patrol boats (and armed with depth charges), namely , Lolita, Steady Hour, , Marlean, and ; and four unarmed Naval Auxiliary Patrol boats. Prelude The Japanese Navy used five Ko-hyoteki-class midget submarines in an unsuccessful operation against US battleships during the attack on Pearl Harbor. The navy hoped that upgrades to the submarines, intensified crew training, and the selection of a less well defended target would lead to better results and an increased chance of the crews of the midgets to return alive from their mission. Therefore, on 16 December 1941, the navy initiated plans for a second midget submarine operation. The plans called for two simultaneous attacks against Allied naval vessels in the Indian and South Pacific oceans. These attacks were intended as diversions ahead of the attack on Midway Island in the North Pacific, with the Japanese hoping to convince the Allies that they intended to attack to the south or west of their conquests. Eleven submarines of the 8th Submarine Squadron were to carry out the two attacks, the five submarines of the Western Attack Group in the Indian Ocean, and the six submarines of the Eastern Attack Group in the Pacific Ocean. The submarine groups were to select a suitable port of attack, based on their own reconnaissance. The Western Attack Group selected the port of Diégo-Suarez in Madagascar. This attack—which occurred at nightfall on 30 May and resulted in the damaging of the battleship and the sinking of the tanker British Loyalty—came 22 days after the British captured the port from Vichy France at the beginning of the Battle of Madagascar. The four potential targets for the Eastern Attack Group were Nouméa, Suva, Auckland and Sydney. Identified by reconnaissance flights conducted by Warrant Flying Officer Nobuo Fujita of the Imperial Japanese Navy flying from I-25; commencing 17 February over Sydney Harbour, and the eastern Australian harbours of Melbourne and Hobart (1 March), followed by the New Zealand harbours of Wellington (8 March) and Auckland (13 March). I-21 and I-29 were sent to select the final target, with I-29 sailing to Sydney. On the evening of 16 May, I-29 fired on the Soviet merchant vessel Wellen, from Newcastle, New South Wales. Although Wellen escaped with minimal damage, shipping between Sydney and Newcastle was halted for 24 hours while aircraft and all available anti-submarine ships from Sydney, including Dutch light