| Year | Date | Historical Events |
| 1941 | Feb 1 | Keel laid down by the Mare Island Naval Shipyard, Vallejo, CA. |
| | Oct 22 | Launched. |
| 1942 | Jan 31 | Commissioned with LCDR. Jack H. Lewis in command.
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| | May 22 | Trigger sailed for Hawaii. |
| | May 29 | Trigger arrived at Pearl Harbor, HI. |
| | May 29 | Trigger sortied for Midway Island with Task Group 7.2 (TG 7.2) on 29 May in anticipation of a Japanese attack on that island. Her station during the ensuing Battle of Midway was Northeast of Midway Island. She was ordered back to Pearl Harbor on 9 June. |
| | Jun 22 | Trigger got underway for the Aleutian Islands to patrol an area West of Cape Wrangell, Attu Island. She encountered 6 destroyers, 3 freighters and a patrol boat, attacking none, before calling at Dutch Harbor on 8 August enroute back to Hawaii.
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| | Aug 13 | Trigger arrived at Pearl Harbor, HI. |
| | Sep 23 | Trigger's 2nd war patrol, with CDR. Roy S. Benson in command, took her to Japanese home waters. |
| | Oct 5 | A vessel appeared, coming toward Trigger. She fired 2 torpedoes and heard one hit. She then surfaced and gave chase, only to have the target again fire. The submarine missed with more torpedoes and then discontinued the pursuit.
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| | Oct 17 | Trigger made a surface attack on a freighter off the Bungo Suido. She fired 2 spreads of torpedoes which sank Holland Maru with her guns still firing. That night, Trigger fired 4 torpedoes at a destroyer but failed to score a hit. |
| | Oct 20 | Trigger fired a spread of 4 torpedoes in a surface attack on a 10,000 ton tanker. 2 torpedoes hit the enemy ship as it turned in an attempt to ram. Trigger heard a heavy explosion as either gasoline, magazines or boilers blew up. |
| | Dec 3 | Trigger departed on her 3rd war patrol. |
| | Dec 20 | Trigger began planting a minefield off Inubo Saki, Honshu. Trigger planted the Northern half of the field and was working on the Southern part when a cargo ship passed her, heading into the newly laid mines. |
| | Dec 20 | (Cont'd.)
Five minutes later, a violent explosion rocked the freighter which sank as an escort circled her. The submarine later heard another explosion and, when she surfaced the next day, found the field was covered by smoke. |
| | Dec 22 | (Cont'd.)
The submarine fired one more torpedo into the ship and, when last seen, Teifuku Maru was awash forward with her screws nearly out of the water. |
| | Dec 22 | Trigger sighted a ship approaching from Uraga and made a surface attack. A spread of 3 torpedoes produced 1 hit forward of the bridge, and the target started to settle by the bow. |
| | Dec 31 | Trigger attacked a cargo ship loaded with planes. Trigger fired 3 torpedoes and watched 2 hit. The target began to list to starboard and was down by the bow. Sound reported a heavy secondary explosion. |
| | Dec 31 | (Cont'd.)
The submarine came up to periscope level and saw the freighter with her stern high out of the water and a destroyer approaching. She went deep and when she next came up for a look, there was nothing to be seen. |
| 1943 | Jan 10 | A Japanese destroyer approached Trigger, and she fired 3 torpedoes. 1 hit under the well deck and another hit the target's stern. Soon, the Minekaze class destroyer Okikaze sank on an even keel. |
| | Jan 22 | Trigger returned to Midway Island. |
| | Feb 13 | Trigger stood out of Midway Island on her 4th war patrol, to patrol off the Palau Islands. |
| | Feb 27 | Trigger fired 4 torpedoes at a freighter, but the target managed to steer between them. Heavy air cover prevented a second attack. |
| | Mar 4 | Trigger attacked a freighter in a rain squall, but all 3 of her torpedoes missed. |
| | Mar 15 | (Cont'd.)
Trigger then fired 3 more torpedoes at the right lead ship. When she surfaced again, there was nothing to be seen. Trigger was later officially credited with having sunk the Momoha Maru, a 3103 ton cargo ship.
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| | Mar 15 | ( Cont'd.)
That night, Trigger fired 6 torpedoes at a ship that was being towed by a smaller freighter. 5 of the torpedoes missed, and the 6th made a circular run and passed over Trigger's engine room. A shaken crew broke off the attack. |
| | Mar 15 | Trigger sighted a convoy steaming in 2 columns. She fired 3 torpedoes at each of the leading ships. She hit the lead freighter in the left hand column twice but missed her target on the right because it unexpectedly changed course. |
| | Mar 20 | Trigger fired 3 torpedoes at the lead ship in a convoy of 4 cargomen. 1 hit caused the target to list 10 degrees to port and stop, but it soon got underway and rejoined the convoy. |
| | Apr 6 | Trigger terminated the patrol at the Submarine Base, Pearl Harbor, HI. |
| | Apr 30 | Trigger's 5th war patrol returned her to Japanese home waters. Trigger lay athwart the projected track of Admiral Koga returning from Truk. Koga's task force came in sight the morning of 22 May, but zigged away, out of range, "a bitter disappointment". |
| | May 28 | Trigger contacted 2 freighters off Iro Saki and launched 3 torpedoes at the larger. 1 hit it's target aft. When last seen, the ship was down by the stern. |
| | May 29 | Trigger fired a spread of 3 torpedoes at a small cargo ship. 2 missed and the 3rd exploded prematurely. She then launched a 4th which apparently hit but failed to explode.
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| | Jun 1 | Trigger sighted 2 columns of smoke. She closed the range toward a firing position, made out 2 cargo ships, and fired a spread of 3 torpedoes at each target. Hit in her stern, the lead ship, Noborikawa Maru, sank immediately. |
| | Jun 1 | (Cont'd.)
The second ship saw the torpedo wakes, turned and passed between them. Trigger then fired a torpedo at the oncoming ship. If the torpedo reached the target, it failed to explode.
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| | Jun 10 | Trigger sighted an aircraft carrier protected by 2 destroyers. She closed and sent 6 torpedoes streaking onward against Koga's flagship. The submarine heard 4 explosions as she went deep to avoid the escorts which kept her down for several hours. |
| | Jun 10 | (Cont'd.)
Yet 2 missed ahead, and 1 failed to explode. The damaged Hiyo limped into Tokyo Bay and was out of action for almost a year. Lockwood, who knew Hiyo's fate, was furious. Had the torpedoes functioned correctly, Benson would have claimed her. |
| | Jun 11 | Trigger began her return voyage to Pearl Harbor, HI. Just after her triumphant return, the MK. 14 torpedo's defective magnetic exploder was ordered deactivated.
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| | Sep 1 | After a yard overhaul, Trigger now in the charge of CDR. Robert Edson "Dusty" Dornin was ready to begin her 6th war patrol. It took her into the East China Sea, off the China coast, North of Formosa. |
| | Sep 17 | Trigger made 2 hits on a Japanese freighter, but both torpedoes proved to be duds. The next day, she again contacted the same ship and fired 4 torpedoes at her. 1 struck the Yowa Maru, and the 6435 ton cargo ship slid beneath the waves.
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| | Sep 21 | Trigger was patrolling North of the Hoka Sho light when she sighted a convoy of 3 tankers and 3 freighters protected by Japanese planes. The submarine attacked the tankers first, firing 3 torpedoes at the leader and 3 at the second. |
| | Sep 21 | (Cont'd.) 1 hit aft on the lead tanker, 1 torpedo hit the 2nd tanker amidships, and it broke in half beneath the stack and sank immediately. Trigger turned and fired 3 torpedoes at the 3rd tanker. All torpedoes missed. |
| | Sep 21 | (Cont'd.) Trigger fired 2 torpedoes at the 3rd freighter and scored 2 hits on the target which went down by the bow. The submarine then made 2 more attacks on the freighter, but all of her torpedoes either missed or were duds. |
| | Sep 21 | (Cont'd.) During the 3 and one-half hours of action, Trigger sank 2 tankers, Shiriya and Shoyo Maru, and a freighter, Argun Maru, for a total of 20,660 tons of enemy shipping. |
| | Sep 30 | Trigger returned to Midway Island to be refitted and rearmed.
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| | Oct 22 | The East China Sea and Yellow Sea were Trigger's objective for her seventh war patrol. She stood out of Midway Island and proceeded to her patrol area. |
| | Nov 1 | Trigger sighted a convoy in 2 columns. She fired a spread of 3 torpedoes at them. 1 torpedo struck the nearer freighter in her bow and 1 hit the farther ship amidships. Trigger saw the nearer ship go down by the bow. |
| | Nov 2 | Trigger fired 3 torpedoes at a freighter and scored 1 hit. She attacked the ship again with a spread of another 3. 2 of them hit forward, and Yawata Maru went down, bow first, in a vertical plunge. |
| | Nov 2 | 2 hours and 25 minutes later, Trigger fired 3 torpedoes at a 7148 ton transport. All torpedoes hit the ship, and Delagoa Maru disintegrated. |
| | Nov 5 | Trigger attacked a convoy of 3 cargo ships. Trigger fired 4 torpedoes before going deep to avoid the escort which dropped 20 depth charges. Trigger came to periscope depth and was greeted by 5 near bomb misses.
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| | Nov 13 | Trigger made a submerged approach on a convoy of 9 merchantmen and 4 escorts. With empty bow tubes. She emptied her stern tubes at the last and biggest ship. Trigger came to periscope depth, to learn that her target had gone down. |
| | Nov 21 | Trigger sighted a cargoman and fired 4 torpedoes. 2 hits started the victim down by the bow as the submarine's crew took turns at the periscope to watch the Eizan Maru sink. |
| | Dec 8 | Trigger arrived at Pearl Harbor, HI. |
| 1944 | Jan 1 | Trigger stood out to sea to begin her eighth war patrol, this time in the Truk-Guam shipping lanes. |
| | Jan 31 | (Cont'd.)She caught up with the convoy again and fired 5 torpedoes at the last ship. 2 hits produced flames that reached masthead height and several secondary explosions that marked the end of the 11,933 ton converted submarine tender Yasukuni Maru. |
| | Jan 31 | Trigger contacted a convoy of 3 ships accompanied by 2 Fubuki class destroyers. The submarine scored 2 hits on the coastal minelayer Nasami which disappeared in a cloud of smoke and debris. |
| | Feb 23 | Trigger terminated the patrol when she arrived at Pearl Harbor, HI. |
| | Mar 23 | Trigger, in the able hands of CDR. Frederick J. "Fritz" Harlfinger II, still with "Ned" Beach as Executive Officer, headed for the Palau Islands on her 9th war patrol. |
| | Apr 8 | (Cont'd.) Trigger loosed 4 torpedoes at the convoy and went deep as several more escorts joined the attack. On her way down, she heard 4 explosions. Trigger ran at 300 feet or more for 17 hours as 6 escorts dogged her trail. |
| | Apr 8 | (Cont'd.) Trigger received numerous depth charges. 6 exploded extremely close. When she surfaced, her forward torpedo room was flooded to her deck plates, the hull air induction and most compartments were in about the same condition. |
| | Apr 8 | (Cont'd.) The bow planes, trim pump, sound gear, and both radars were all dead. Her radio antenna was grounded, and the submarine could not transmit. The crew spent 4 days making repairs "by use of spares, baling wire, and considerable ingenuity". |
| | Apr 8 | Trigger contacted a convoy of approximately 20 large ships with an estimated 25 escorts and closed to attack. When she raised her periscope, she saw a destroyer 150 feet away firing at the scope and attempting to ram. |
| | Apr 14 | Trigger met submarine Tang (SS-306) and exchanged information by line gun. |
| | Apr 15 | Trigger’s Executive Officer went on board Tang by a rubber boat, to borrow an air compressor part and to make plans for a coordinated search and attack. |
| | Apr 18 | Tang’s Executive Officer delivered spare parts for the air compressor to Trigger, and she continued on patrol.
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| | Apr 26 | (Cont'd.) Suddenly, a terrific explosion blew up one of the closer ships. One of the more distant ships stood straight up on her bow and then sank immediately. |
| | Apr 26 | Trigger contacted a convoy of 6 ships off the Eastern Palau Islands. She fired 6 torpedoes, at 4 ships that were closely bunched and overlapping. 4 hits were seen and heard from a big explosion on each ship. |
| | Apr 27 | At 6 minutes after midnight, Trigger fired 3 torpedoes at a group of ships and heard 1 timed explosion. At 0157, she fired 4 torpedoes at a damaged cargo ship and 2 at an escort. The cargo ship received 2 more hits. |
| | Apr 27 | (Cont'd.) 5 minutes later, the submarine fired 3 stern tubes at a group of 3 escorts, and the middle one disappeared in a cloud of smoke. |
| | Apr 27 | (Cont'd.) During the attack, Trigger sank the 11,739 ton passenger-cargo ship Miike Maru and heavily damaged the destroyer escort Kasado, the 9467 ton cargo ship Hawaii Maru, and the 8811 ton cargo ship Asosan Maru. |
| | May 20 | Trigger returned to Pearl Harbor, HI. |
| | May 24 | Trigger headed for the United States for a major overhaul. |
| | May 31 | Trigger arrived at San Francisco, CA. |
| | Sep 11 | Trigger returned to Pearl Harbor, HI. after overhaul. |
| | Sep 24 | Trigger got underway to take station off the East Coast of Formosa and perform life guard patrol for bomber strikes due on 12 October. The morning of the strikes, she rescued a pilot from the aircraft carrier Bunker Hill (CV-17). |
| | Oct 19 | Trigger contacted a convoy of 2 Takao class heavy cruisers, 1 Nagara class cruiser, 2 other light cruisers, and several destroyers with air cover. Trigger had no chance to fire but reported the contact. |
| | Oct 30 | Trigge fired 4 torpedoes at a tanker but missed. She then fired another 4 from her stern tubes and heard 1 hit the target before running up the periscope to watch the other 3 blow off part of the stern, but the ship did not sink. |
| | Oct 30 | (Cont'd.) Trigger went deep as 78 depth charges were rained down on her within the next hour, but caused no damage. The damaged 10,021 ton tanker Takane Maru was later sunk by submarines Salmon (SS-182) and Sterlet (SS-392). |
| | Oct 31 | Trigger received word from Salmon that she had been heavily damaged by depth charges and was unable to submerge. Trigger rendezvoused with Salmon that night and was joined by Silversides and Sterlet to escort the damaged submarine to Saipan. |
| | Nov 3 | Trigger arrived at Tanapag Harbor. |
| | Nov 10 | Trigger departed with 6 other submarines but was ordered to discontinue her patrol. |
| | Nov 17 | Trigger returned to Guam, Marianas Islands. |
| | Dec 28 | Trigger headed for the Bungo Suido-Kii Suido area to begin her 11th war patrol. |
| 1945 | Jan 3 | Trigger sighted a light, and radar made a doubtful contact. 30 minutes later, a torpedo passed by her starboard side. She reversed course and cleared the area but returned 2 days later. |
| | Jan 5 | Trigger sighted a periscope at 2,000 yards, and—realizing that instead of hunting, she was being hunted, she slipped away.
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| | Jan 29 | Trigger made radar contact from 23,000 yards on a large convoy with 6 escorts and well covered by aircraft. As she closed, an enemy bomber turned and started in as radar picked up another plane coming in astern at 5,000 yards. Trigger went deep. |
| | Feb 3 | Trigger returnd to Guam, Marianas Islands. |
| | Mar 11 | Trigger, with new skipper CDR. David R. Connole, stood out to sea to begin her 12th war patrol and headed for the Nansei Shoto area. |
| | Mar 18 | She attacked a convoy West of the islands, sinking the cargo ship Tsukushi Maru No.3 and damaging another. The attack was reported on 20 March. |
| | Mar 26 | Trigger was ordered to join a wolf pack and to acknowledge receipt of the message. A weather report came from the submarine that day but no confirmation of her having received the message. The weather report was Trigger's last transmission. |
| | Mar 27 | Postwar records indicate that Trigger torpedoed and sank the repair ship Odate. |
| | Mar 28 | Postwar Japanese records showed a Japanese aircraft detected and bombed a submarine. Surface ships were then guided to the spot and delivered an intensive depth charging. After two hours, a large oil slick appeared.
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| | Jul 11 | Struck from the Naval Register. |