Ro-111 was an Imperial Japanese Navy Ro-100-class submarine. Completed and commissioned in July 1943, she served in World War II, operating in the Indian Ocean — where she sank a cargo ship and a troopship — and off the Admiralty Islands in the Pacific Ocean. She was sunk in June 1944 during her fifth war patrol.
Design and description
The Ro-100 class was a medium-sized, coastal submarine derived from the preceding Kaichū type. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had a double hull and a 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 Ro-100s 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 eight torpedoes. They were also armed with two single mounts for Type 96 anti-aircraft guns or a single L/40 AA gun.
Construction and commissioning
Ro-111 was laid down as Submarine No. 402 on 20 August 1942 by Kawasaki at Kobe, Japan. She had been renamed by the time she was launched on 26 January 1943. She was completed and commissioned on 19 July 1943.
Service history
July–November 1943
Upon commissioning, Ro-111 was attached to the Sasebo Naval District and assigned to Submarine Squadron 11 for workups. She was reassigned to Submarine Squadron 7 in the 8th Fleet on 20 July 1944. On 31 October 1943, she was reassigned to Submarine Division 30 in Submarine Squadron 8 in the Southwest Area Fleet, and she departed Kure, Japan, that day bound for Penang in Japanese-occupied British Malaya. After stopping briefly at Singapore on 16 November 1943, she got back underway the same day and reached Penang on 23 November 1943.
First war patrol
On 6 December 1943, Ro-111 departed Penang to begin her first war patrol, tasked with raiding Allied shipping in the Bay of Bengal. She attacked a British 12-ship convoy — Convoy JC.30, bound from Swansea, Wales, to Calcutta, India — in the Indian Ocean southeast of Madras, India, on 23 December 1943. One of her torpedoes struck the British 7,934-gross register ton armed cargo ship Peshawur, which was carrying 150 tons of explosives and 1,983 tons of general cargo. Peshawur′s crew — some of whom mistakenly believed an acoustic homing torpedo had hit their ship rather the wakeless Type 95 torpedo Ro-111 actually had fired — abandoned ship, and she sank two hours later. The Royal Australian Navy corvette rescued all 134 men on board Peshawur, including her entire crew of 125 and all nine of her embarked gunners. Ro-111 returned to Penang on 29 December 1943.
Second war patrol
Ro-111 put to sea on 7 January 1944 to conduct her second war patrol, tasked with laying mines off Ceylon and then attacking Allied shipping east of Ceylon. She laid ten Type 3 mines off Elephant Rock, Ceylon, on 10 January 1944, but otherwise her patrol was uneventful, and she returned to Penang in late January 1944.
Third war patrol
Ro-111 again left Penang on 1 February 1944 to begin her third war patrol. She again operated off Ceylon, laying more mines and patrolling Ceylonese waters without finding any targets. She returned to Penang on 23 February 1944.
Fourth war patrol
At 09:00 on 7 March 1944, Ro-111 put to sea from Penang to begin her fourth war patrol, briefly escorted by the torpedo boats and as she departed. Her patrol area was in the vicinity of Calcutta. In the Bay of Bengal on 16 March 1944, she attacked Convoy HC.44, which was on a voyage from Calcutta to Chittagong, India. One of her torpedoes hit the Indian armed troopship , which was serving as the flagship of the convoy vice-commodore, at . El Madina broke in two, and her stern section sank a few minutes after the torpedo hit. While the rest of the convoy and all of its escorts left the area, the Norwegian steamer stopped her engines and rescued El Madina′s 814 survivors. The other 380 men aboard El Madina lost their lives.
Ro-111 arrived at Penang on 25 March 1944, the same day that Submarine Division 30 was disbanded and she was reassigned to Submarine Division 51 in Submarine Squadron 7 in the Southwest Area Fleet. On 28 March 1944 she departed Penang and set course for Sasebo, Japan, which she reached in April 1944 for a refit and an overhaul.