[1] For surface running, the boats were powered by two 500-brake-horsepower (373 kW) diesel engines, each driving one propeller shaft.

[4] Upon commissioning, Ro-116 was attached formally to the Yokosuka Naval District and was assigned to Submarine Squadron 11 for workups.

[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][5] The picket line was tasked with providing warning of any move toward the Palau Islands by Allied invasion forces.

[8] 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] 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 / 0.883°N 149.233°E / 0.883; 149.233 ('Ro-116).

[9][13] 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.