[13] From Hong Kong, the submarines began operations in support of a Japanese blockade of China and patrols of China′s central and southern coast.

[13] In an effort to reduce international tensions over the conflict in China, Japan withdrew its submarines from Chinese waters in December 1938.

[4] While in reserve, I-1 underwent a refit, during which impulse tanks were installed on her Type 15 torpedo tubes and her collapsible radio masts were removed.

[5] His chief of staff briefed them on the upcoming attack on Pearl Harbor, which would bring Japan and the United States into World War II.

[5] As the Imperial Japanese Navy began to deploy for the upcoming conflict in the Pacific, the rest of Submarine Squadron 1 got underway from Yokosuka on 16 November 1941, bound for the Hawaiian Islands.

After an overnight stop in Tateyama Bight, she got underway for Hawaii, proceeding at flank speed to catch up with her squadron mates and remaining on the surface until within 600 nautical miles (1,100 km; 690 mi) of Oahu.

[5] At 07:30 on 7 December 1941, I-1 sighted an Aichi E13A1 (Allied reporting name "Jake") floatplane returning to the heavy cruiser Tone after a reconnaissance flight over Lahaina Roads off Maui.

[5] In the following days, she was attacked repeatedly by aircraft; although she suffered no damage, she began to keep her negative buoyancy tank flooded when surfaced so that she could dive more quickly.

[5] She arrived off Hilo on 30 December and conducted a periscope reconnaissance of the harbor, sighting the U.S. Navy seaplane tender USS Hulbert (AVD-6)—which she misidentified as a small transport—moored there.

[5] On 9 January 1942, she was ordered to divert from her patrol and search for the United States Navy aircraft carrier USS Lexington (CV-2), which the submarine I-18 had sighted northeast of Johnston Island.

Shortly after she left Staring Bay, her starboard diesel engine′s crankshaft broke down, but she pushed on, conducting most of her patrol on only one shaft.

[5] On 18 April 1942, 16 United States Army Air Forces B-25 Mitchell bombers launched by the aircraft carrier USS Hornet (CV-8) struck targets on Honshu in the Doolittle Raid.

[5] One B-25 targeted Yokosuka, and the members of I-1's crew on deck saw it damage the drydocked aircraft carrier Ryūhō, which was undergoing conversion from the submarine tender Taigei.

[5] In mid-July 1942, an unidentified American warship—possibly the United States Coast Guard cutter USCGC Onondaga (WPG-79)—attacked I-1 in the North Pacific Ocean south of Adak Island and pursued her for 19 hours before I-1 finally dived to 260 feet (79 m) and escaped.

[5] In late August 1942, I-2 underwent work at Yokosuka Navy Yard in which her after 140-millimeter (5.5 in) deck gun was removed and a mounting for a waterproofed 46-foot (14 m) Daihatsu-class landing craft was installed abaft her conning tower, which improved her ability to transport supplies to Japanese forces ashore in the Solomon Islands.

[5] She embarked 71 wounded SLNF personnel and the cremated remains of 13 others, recovered the Daihatsu, and returned to Rabaul, which she reached at 13:30 on 6 October 1942.

Allied intelligence had warned of her arrival, and a Royal Australian Air Force Lockheed Hudson Mark IIIA patrol bomber of No.

[5] While I-1 was at sea, a floatplane from I-7 made a reconnaissance flight over Espiritu Santo on 17 October 1942, finding a significant Allied naval force there.

At 06:30 on 12 January 1943 she put to sea to conduct Daihatsu launch tests, but was back at her anchorage at 08:30 to repair the air induction valve for her diesel engines.

[5] At 16:00 on 24 January 1943, she departed Rabaul bound for Guadalcanal, where she was to deliver her cargo at Kamimbo Bay on the island's northwest coast.

[5] For its part, the Japanese 6th Fleet warned Submarine Division 7 that Allied motor torpedo boats were operating in the vicinity of Kamimbo Bay and advised them to unload supplies only after dark.

[5][14] When one of I-1's lookouts sighted Kiwi and Moa—misidentifying them as torpedo boats—I-1 turned to port and submerged, diving to 100 feet (30 m), and rigging for silent running.

[5][14] It disabled I-1's pumps, steering engine, and port propeller shaft, and ruptured her high-pressure manifold, sending a fine water mist across her control room.

[5][14] Believing that the New Zealanders intended to board and capture I-1, he prepared the submarine to repel boarders, sending a reserve gun crew on deck to man her deck gun, ordering all surviving officers to arm themselves with their swords, and issuing Arisaka Type 38 carbines to the four best marksmen among the surviving crew.

[5][14] Kiwi damaged her own stem and asdic gear, but she punched a hole in one of I-1's main ballast tanks and disabled all but one of the submarine′s bilge pumps, and I-1 developed an increasing starboard list.

[5][14] Damaged and with her 4-inch (102 mm) gun overheating, Kiwi pulled away from I-1[15] and Moa continued the chase, firing at I-1 while illuminating her with a searchlight and star shells.

[5][14] She hit I-1 repeatedly, but the submarine′s upper armor deflected some of Moa's shells and splashes from near misses put out the fire that had been raging in her Daihatsu.

The submarine rescue vessel USS Ortolan (ASR-5) inspected the wreck of I-1 on 13 February 1943, and her divers recovered five code books and other important communications documents.

[12] Ultimately, the U.S. Navy reportedly salvaged code books, charts, manuals, the ship's log, and other secret documents, as well as equipment, from the wreck of I-1.

[5] In 1968, I-1's main deck gun was salvaged and brought to Auckland, New Zealand, aboard the frigate HMNZS Otago[16] for display at the Torpedo Bay Navy Museum.