Before dawn on 14 May 1943, Australian Hospital Ship Centaur was torpedoed by a Japanese submarine off North Stradbroke Island,. Of the 332 aboard all but 64 drowned including 11 of the 12 nurses onboard; the survivors were discovered 36 hours later.
The incident resulted in public outrage as attacking a hospital ship is a war crime under the 1907 Hague Convention which states:
Military hospital-ships, the names of which shall have been communicated to the belligerent Powers at the commencement of. or during the course of hostilities, shall be respected, and cannot be captured or attacked
Centaur’s conversion to a hospital ship was made known to Japan through Geneva and she was painted white with Red Crosses. Whether these were visible to a submariner in the pre dawn light is not certain.
War crimes investigators suspected that CMDR Nakagawa and I-177 were culpable but they were unable to establish this beyond reasonable doubt. However, Nakagawa was charged with ordering the machine-gunning of survivors from torpedoed ships on three different dates in 1944.
He was sentenced to four years imprisonment as a Class B war criminal. He refused to speak about the sinking of Centaur, even to defend himself, until his death in 1991.
The wreck of Centaur was found on 20 December 2009.