Midget Submarine Type A : Imperial Japanese Navy

Japanese Midget submarine which is a composite of two submarines - the Ha-21 and the Ha-14.

The original submarine type was constructed of 6.4mm steel plate in five sections: Forward section incorporating torpedo tubes (22 x 6 feet); forward battery compartment; control room; aft battery compartment (assembled centre section length 38 feet x height 11.5 feet x width 6 feet, weight 14 tons); and aft section incorporating electric motor, drive shaft, contra-rotating propellers and control surfaces (24 x 6 feet, weight 6 tons).

Operational equipment includes 1 gyro compass, 1 magnetic compass, 1 radio receiver, 1 radio transmitter and underwater listening gear. Miscellaneous equipment includes a net cutter, single periscope and circular propeller guard on vertical and horizontal aft planes.

This example comprises the forward section and the battery compartment from the Ha-21, and the control room, aft battery compartment and aft motor section from the Ha-14. A large portion of the forward end of the control room shows evidence of the detonation charge used by the crew to prevent themselves being captured alive.

This is a composite formed from the recovered Ha-14 and the Ha-21 Type A midget submarines which were part of a force of three submarines which launched a surprise attack on Sydney Harbour during the night of 31 May/1 June 1942 in an attempt to destroy Australian and American warships. The principal targets of the attack were the cruisers USS Chicago and HMAS Canberra, neither of which was hit.

The only casualty of the attack was the depot ship HMAS Kuttabul, which was torpedoed by the M24 submarine with the loss of 21 sailors, 19 of whom were members of the Royal Australian Navy (RAN) and the remaining 2 of the Royal Navy (RN).

The Ha-14 and the Ha-21 were sunk in the harbour and retrieved with the bodies of their four Japanese submariners. Their remains were recovered and cremated with full military honours with their ashes returned to Japan via a neutral country later in 1942. In 1943 the composite submarine was taken on an extensive fund raising tour from Sydney to Adelaide to raise money for the war effort, before being transferred to the Australian War Memorial.

The third submarine used in the attack was not found until 2006 off the northern beaches of Sydney by amateur divers. The Japanese designation for this submarine is not known. The designation M24 is that which was given to it by Allied personnel, with reference to its mother submarine, the I-24.

• Lower hull crew hatch cover : Midget Submarine Type A, Imperial Japanese Navy