Japanese submarine I-178

I-178 was a KD7 type Kaidai-class submarine operated by the Imperial Japanese Navy during World War II. Built in 1942, the submarine made two patrols off the east coast of Australia during 1943, before going missing sometime after 17 June 1943

Design and construction
The KD7 type Kaidais were 346 ft long and displaced 1,833 t when surfaced. The diesel-electric propulsion system provided a maximum speed of 23 kn when surfaced or 8 kn when submerged. The boats could operate for 75 days before resupply. Armament consisted of six forward-facing torpedo tubes firing Long Lance torpedoes (with 14 carried), a 4.7-inch deck gun, and a 25-millimetre anti-aircraft gun.

The submarine was built at the Mitsubishi Yard. She was completed in 1942.

Operational history
Assigned to Submarine Squadron Three of the Sixth Fleet, I-178 sailed from Japan on 30 March 1943, and reached Truk on 7 April. Three days later, the submarine left to commence a patrol off the eastern coast of Australia, supporting sister boat I-177. At 18:45 on 27 April 1943, the submarine torpedoed the Liberty ship SS Lydia M. Child 90 miles off the coast of Newcastle, New South Wales. There were no casualties among the freigher's 62 crew, who were all rescued the next day. I-178 escaped despite multiple attempted bombing runs by a Catalina from No. 11 Squadron RAAF.

She returned to Truk on 18 May, but was ordered to sail again two days later, returning to the Australian coast. The patrol was initially uneventful, but after receiving a routine radio signal from I-178 on 17 June, the submarine was never heard from again.

Fate
On 4 August, the submarine was declared lost with all hands. She was struck from the Navy List on 1 September.

Claims for sinking the submarine vary, with different sources identifying the responsible party as the submarine chaser USS SC-669 or USS SC-699 off Espirito Santo on 29 May 1943, the destroyer USS Patterson (DD-392) near the Solomon Islands on 25 August 1943, or three Bristol Beauforts of No. 32 Squadron RAAF off Coffs Harbour, New South Wales on 17 June.