I-18 was one of five Type C cruiser submarines of the C1 sub-class built for the Imperial Japanese Navy. During World War II, she operated as the mother ship for a midget submarine during the attack on Pearl Harbor and the attack of Diego-Suarez, conducted a war patrol in the Indian Ocean, and served in the Guadalcanal campaign before she was sunk in February 1943.
Design and description
The Type C submarines were derived from the earlier KD6 sub-class of the with a heavier torpedo armament for long-range attacks. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had 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 C1s had a range of at ; submerged, they had a range of at .
The boats were armed with eight internal bow torpedo tubes and carried a total of 20 torpedoes. They were also armed with a single /40 deck gun and two single or twin mounts for Type 96 anti-aircraft guns. They were equipped to carry one Type A midget submarine aft of the conning tower.
Construction and commissioning
Ordered under the 3rd Naval Armaments Supplement Programme and built by the Sasebo Naval Arsenal at Sasebo, Japan, I-18 was laid down on 25 August 1937 with the name Submarine No. 38. Launched on 19 July 1939, she was completed and commissioned on 31 January 1941, by which time she had been renamed I-18.
Service history
Pre-World War II
Upon commissioning, I-18 was attached to the Yokosuka Naval District, assigned to Submarine Division 2 in Submarine Squadron 1 in the 6th Fleet In the autumn of 1941, she underwent conversion into a mother ship for a Type A midget submarine. The submarines , , , and also underwent the conversion. By 15 November 1941, I-18 was a part of Submarine Division 3 — which also included and I-20 — in Submarine Squadron 1 in the 6th Fleet.
At the Kure Navy Club in Kure, Japan, on 17 November 1941, the commander of Submarine Division 3 briefed the commanding officers of the five converted submarines on the upcoming attack on Pearl Harbor and on the role of their submarines in it. He had been designated the commander of the Special Attack Unit, made up of all five submarines, each of which was to launch a Type A midget submarine off Pearl Harbor so that the midget submarines could participate in the attack. I-22 was to serve as flagship of the Special Attack unit.
On 18 November 1941, the five submarines moved from Kure to the Kamegakubi Naval Proving Ground, where each embarked a Type A midget submarine. At 02:15 on 19 November 1941, the five submarines got underway from Kamegakubi bound for the Hawaiian Islands, taking a direct route that took them south of Midway Atoll. While at sea, they received the message "Climb Mount Niitaka 1208" () from the Combined Fleet on 2 December 1941, indicating that war with the Allies would commence on 8 December 1941 Japan time, which was on 7 December 1941 on the other side of the International Date Line in Hawaii.
World War II
Pearl Harbor
At 02:15 on 7 December 1941, I-18 launched her midget submarine, No. 17, south of Oahu about from the entrance to Pearl Harbor. No. 17 was depth charged and sunk with the loss of its two-man crew outside the harbor in Keehi Lagoon. Its wreck was discovered resting in of water on 13 June 1960, and the United States Navy submarine rescue ship refloated it on 6 July 1960, finding no human remains inside. At the request of the Government of Japan, the United States returned the wreck to Japan, where it is displayed at the Naval Academy Etajima in Etajima.
I-18 and the other four "mother" submarines proceeded to the planned recovery area for their midget submarines west of Lanai, where they spent the night of 7–8 December 1941. None of the midget submarines returned. Early on 9 December 1941, I-18, I-20, and I-24 received orders to leave the recovery area. I-18 departed the Hawaiian Islands on 12 December 1941 and arrived at Kwajalein on 22 December 1941.