Japanese submarine Ro-116

Upon commissioning, Ro-116 was attached formally to the Yokosuka Naval District and was assigned to Submarine Squadron 11 for workups.[4] She called at the 3rd Fuel Depot at Tokuyama, Japan, from 28 to 29 March 1944 to refuel.[4]

Ro-116 got underway from Japan on 31 March 1944 along with the submarine Ro-117 for her first war patrol, ordered to intercept an Allied task force operating in the vicinity of the Palau Islands.[4] She did not find the task force, and returned to Japan on 13 April 1944.[4]

On 4 May 1944, Ro-116 was reassigned to Submarine Division 51 in Submarine Squadron 7 in the 6th Fleet.[4] She departed Kure, Japan, that day bound for Saipan in the Mariana Islands, which she reached on 10 May 1944.[4]

Ro-116 got underway from Saipan on 15 May 1944 for her second war patrol with orders to join the submarines Ro-104, Ro-105, Ro-106, Ro-108, Ro-109, and Ro-112 in forming a submarine picket line north of the Admiralty Islands designated Scouting Line NA.[4][5] The picket line was tasked with providing warning of any move toward the Palau Islands by Allied invasion forces.[4]

On 18 May 1944, U.S. Navy signals intelligence personnel intercepted and decrypted Japanese signals indicating the formation of Scouting Line NA between Truk and the Admiralties.[4] A hunter-killer group composed of the destroyer escorts USS England (DE-635), USS George (DE-697), and USS Raby (DE-698) departed Purvis Bay in the Solomon Islands to attack the submarines involved.[4]

At 01:20 Lima Time on 24 May 1944, Ro-116 was on the surface 225 nautical miles (417 km; 259 mi) north-northwest of Kavieng on New Ireland when George gained radar contact on her at a range of 17,000 yards (15,500 m).[4] Ro-116 submerged at 01:28, causing George to lose contact.[4] At 01:50, however, England made sonar contact on Ro-116 at a range of 750 yards (690 m).[4] Operating at a depth of 170 feet (52 m), Ro-116 began to emit sound impulses to jam England′s sonar and to make violent evasive maneuvers intended to disrupt England′s sonar by creating underwater wakes.[4] England aborted her first two attack runs, then fired a barrage of 24 Hedgehog projectiles, at least three of which hit and sank Ro-116 at 00°53′N 149°14′E.[4] After sunrise, debris was recovered from the ocean's surface in the area.[4]

On 25 June 1944, the Imperial Japanese Navy declared Ro-116 to be presumed lost north of the Admiralty Islands with all 56 men on board.[4] The Japanese struck her from the Navy list on 10 August 1944.[4]