Ro-45 was an Imperial Japanese Navy Kaichū type submarine of the K6 sub-class. Completed and commissioned in January 1944, she served in the central Pacific Ocean during World War II and was sunk in April 1944 during her first combat sortie. Design and description The submarines of the K6 sub-class were versions of the preceding K5 sub-class with greater range and diving depth. They displaced surfaced and submerged. The submarines were long overall, had a beam of and a draft of . They had an operational diving depth of . For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the K6s had a range of at ; submerged, they had a range of at . The boats were armed with four internal bow torpedo tubes and carried a total of ten torpedoes. They were also armed with a single 40-caliber anti-aircraft (AA) gun and two single AA guns. Construction and commissioning Ro-45 was laid down as Submarine No. 386 on 20 October 1942 by Mitsubishi at Kobe, Japan. She was launched on 21 July 1943 and was renamed Ro-45 on that day. She was completed and commissioned on 11 January 1944. Service history Upon commissioning, Ro-45 was attached to the Maizuru Naval District and assigned to Submarine Squadron 11 for workups. On 14 April 1944, she was reassigned to Submarine Division 34 in the 6th Fleet. She departed Kure, Japan, on 16 April 1944 bound for Truk, which she reached on 27 April 1944. While Ro-45 was at Truk, the aircraft carriers of United States Navy Task Force 58 began two days of airstrikes against Truk on 29 April 1944. On 30 April 1944, during the second day of strikes, the commander of Submarine Squadron 7 ordered Ro-45 and the submarines , , , , , and to intercept Task Force 58. Loss At 06:21 local time on 30 April 1944, the U.S. Navy destroyer made radar contact on an unidentified vessel on the surface south of Truk. The contact disappeared from radar, indicating a submerging submarine. MacDonough subsequently gained sonar contact on the submarine and, with an F6F Hellcat fighter from Fighter Squadron 28 (VF-28) aboard the light aircraft carrier providing spotting support, made two depth-charge attacks. The destroyer also joined