USS Thresher (SS-200) - Eleventh and Twelfth Patrols

Eleventh and Twelfth Patrols

Thresher’s 11th war patrol (this one under command of Duncan C. MacMillan, Class of 1926) took her to the South China Sea south of Formosa. While cruising on the surface on 10 January 1944, Thresher sighted a pair of masts, low on the horizon, and quickly dove to avoid possible detection. Coming to periscope depth soon thereafter, she approached cautiously, keeping in mind the ship may have been the advance screen of a convoy. The contact proved to be a 150-ton trawler. Thresher battle-surfaced, commencing fire at 6,000 yards (5,500 m); the trawler sank after Thresher expended 45 5 inches (130 mm) shells, 1,000 rounds of .50-caliber (12.7 mm); and 770 20 millimetres (0.79 in) rounds.

Thresher next set course for the Luzon Strait, between Batan Island and Luzon, in the Philippines. At 11:43 on 15 January, she came to the surface and spotted a Japanese aircraft carrier with an escorting destroyer soon thereafter. The boat submerged to periscope depth in time to observe two enemy destroyers rapidly approaching. With insufficient time to maneuver for a "down the throat" shot, Thresher went deep and rigged for silent running. The destroyer churned overhead and dropped four depth charges, none close. After remaining overhead two hours, dropping between ten and fifteen more depth charges, the enemy finally turned away, leaving Thresher unscathed.

Again coming to periscope depth at 17:00, Thresher soon sighted a four-ship convoy at 12,000 yards (11,000 m) with a single sub-chaser as escort. Surfacing at 19:11, Thresher began the chase, tracking the convoy by radar. The three leading targets steamed in column, with the escort between the third and fourth merchantmen. Thresher maneuvered to the west to silhouette the targets against the rising moon. The convoy changed course at 21:55, giving Thresher an excellent setup for her stern tubes. At 22:07, the boat let fly from 1,800 yards (1,600 m) with four torpedoes at the lead ship, a 6,960 ton freighter. Thresher observed two hits, and the vessel, its bow in the air, was observed in a sinking condition.

Thresher next fired three bow tubes at the second target, a 4,092 ton freighter. Three torpedoes struck the ship—evidently a tanker—and literally blew her to pieces. The cargo of oil burst into flames and illuminated the night as brightly as day.

The third ship started firing on Thresher with deck guns, passing down the port side at 800 yards (730 m). With the submarine now readily visible, and her stern tubes dry, Thresher dove as bullets from the approaching escort splashed nearby. Thresher counted some 20 explosions from depth charges before the patrol craft left an hour later. Upon surfacing, Thresher was again alone and set off to patrol along the Singapore-to-Japan trade route.

On 26 January, Thresher made radar contact with a small convoy and soon spotted two ships steaming along beneath the overcast night skies. At 00:11, Thresher fired three bow torpedoes at a 1,266-ton freighter, then bent cleared the area. Her "fish" scored a bullseye, and the quarry disappeared within a minute. A second spread, 35 seconds after the first, claimed a 2,205-ton freighter. A third target made off to the south at high speed, "spraying the ocean with five-inch ammunition." Resuming the approach at 00:20, Thresher doggedly tailed the Japanese ship for four hours before reaching a favorable attack position. Firing her last torpedoes at 04:46, Thresher began to build up speed and had just commenced a turn when one torpedo struck the enemy ship, causing a tremendous explosion. The blast slowed the freighter, but its tremendous concussion stopped Thresher dead in the water. All four main engine overspeed trips were actuated; cork insulation flew; lights broke; clocks stopped; and water poured down the antenna trunk. By the time Thresher regained battle readiness, the enemy was too far away to encourage further pursuit. Well within the range of shore-based aircraft, Thresher quit the chase. Escorts, alerted to the fact an American submarine was prowling in the vicinity, arrived on the scene and conducted a three-hour long, futile, depth-charging.

On 28 and 29 January, Thresher patrolled the Formosa-to-Palau route, in the Luzon Strait, before returning via Midway Island to Pearl Harbor where she arrived on 18 February. There, Lieutenant Commander MacMillan was awarded the Navy Cross for his aggressive action during the patrol.

Thresher went to sea again on 18 March 1944, departing Pearl Harbor for the central Caroline Islands. She remained on air-sea rescue ("lifeguard") station during American carrier strikes on Truk, bombarded Oroluk Atoll on 11 April, and photographed islands in that group. The boat played "hide and seek" with numerous enemy aircraft and witnessed several American bombing raids on Truk. She sighted only two enemy ships and was unable to attack either, before she returned to Pearl Harbor on 8 May.