began an attack approach. I-5, which had identified I-20 as a Japanese submarine, managed to break contact with I-20, which had never realized during the encounter that I-5 was Japanese. I-5, , I-16, and I-20 were attached temporarily to the headquarters of the 8th Fleet on 13 April 1942. I-20 delivered 37 tons of cargo at Lae on 15 April 1943 and embarked 42 soldiers. An Allied bomber illuminated her with flares off Lae, but she avoided an attack. I-20′s next supply run was to Kolombangara in the New Georgia Islands, where she delivered food and ammunition on 20 April 1943. She then returned to her Lae runs, calling there on 2 May 1943 to deliver 39 tons of cargo and evacuate 31 soldiers and on 8 May to deliver another 39 tons of cargo on her seventh and final supply run to Lae. Re-attached to 8th Fleet headquarters on 15 May 1943, she proceeded to Japan, where she arrived on 20 May at Yokosuka for an overhaul. Second war patrol With her overhaul complete and reassigned to Submarine Squadron 1, I-20 departed Yokosuka on 4 August 1943 and stopped at Truk from 10 to 19 August before getting back underway to conduct her second war patrol, assigned a patrol area in the New Hebrides. On 30 August 1943, she reported sighting an Allied force including an aircraft carrier and two battleships off Espiritu Santo. On 31 August, she reported that she had torpedoed and damaged the American 10,872-ton tanker W. S. Rheem at . She was never heard from again. Loss The exact circumstances of I-20′s loss remain unknown. I-20 and the submarine both were patrolling in the vicinity of the New Hebrides at the time, and neither returned. U.S. Navy forces reported two successful antisubmarine attacks off Espiritu Santo in early September 1943. The first action took place on 1 September 1943, when the destroyer , operating as part of a hunter-killer group, began a search for a reported Japanese submarine off Espiritu Santo at 10:55. After searching on a north-south axis, she picked up a strong sonar contact at 13:00, and dropped a pattern of ten depth charges set to explode at an average depth of . The attack produced no signs of success, so Wadsworth commenced a second attack, with her depth charges set for an average of . The submarine turned to port just before