I-168 (Japanese submarine)

I-168 (Japanese submarine)
Ship name	I-168
Ship caption	I-168 underway, circa 1942
Ship country	Empire of Japan
Ship order	Kaidai VIa class
Ship builder	Kure Naval Arsenal
Ship laid down	12 December 1937
Ship launch	1 April 1939
Ship commission	20 December 1940
Ship decommission	1 August 1945
Ship status	Sunk 4 July 1943
Ship length	108.7 m
Ship beam	9.3 m
Ship draught	5.1 m
Ship propulsion	Diesel engines; electric motors
Ship speed	23.6 kn (surface); 8 kn (submerged)
Ship range	14,000 nmi at 16 kn
Ship test depth	75 m
Ship capacity	92 officers and men
Ship armament	6 × 533 mm bow torpedo tubes; 1 × 120 mm deck gun; 2 × 25 mm AA

I-168 (Japanese submarine) was a Kaidai VIa-class cruiser submarine of the Imperial Japanese Navy that saw significant action during the Pacific War, most notably at the Battle of Midway where she sank the Yorktown and the destroyer Hammann. Designed for long-range reconnaissance and fleet operations, she participated in Indian Ocean raid operations, Guadalcanal campaign supply missions, and commerce raiding before being lost in mid-1943. Her career intersected with major personalities and units including Isoroku Yamamoto, Chuichi Nagumo, Frank Fletcher, Chester W. Nimitz, and the United States Navy carrier forces.

Design and construction

I-168 was laid down at Kure Naval Arsenal in 1937 and launched in 1939 as part of the Kaidai VI series developed from earlier Kaidai types influenced by German U-boat developments and lessons from the Washington Naval Treaty era. Her hull and internal arrangements reflected design priorities set by the Imperial Japanese Navy General Staff and Yokosuka Naval Arsenal draftsmen for extended Pacific operations supporting the Combined Fleet and 1st Fleet. Armed with six forward 533 mm torpedo tubes carrying Type 93 torpedos and a 120 mm deck gun, she emphasized offensive striking power similar to contemporaries such as I-19 and I-26. Her diesel-electric propulsion provided high surface speed for fleet rendezvous, while her test depth and torpedo reload systems embodied innovations emerging from prewar experiments at Kagoshima and Yokosuka training schools.

Service history

After commissioning in December 1940, I-168 served with Kure Naval District units and was assigned to submarine squadrons of the 6th Fleet under commanders tasked with supporting Operation Z and subsequent Pacific operations. Early wartime patrols included reconnaissance for the Pearl Harbor attack's follow-up operations and patrols in the Marshall Islands and around Wake Island during the War in the Pacific (1941–45). She later took part in the Indian Ocean raid logistics posture supporting the Kido Butai carrier striking force under Isoroku Yamamoto and Chuichi Nagumo, operating in concert with submarines such as I-15 and I-21. Commanding officers rotated through experienced skippers drawn from Naval Academy at Etajima graduates.

Battle of Midway and sinking of Yorktown

Assigned to the submarine screen for the Midway operation, I-168 departed as part of the Operation MI plan coordinated by Isoroku Yamamoto and Chuichi Nagumo to seize Midway Atoll from U.S. Pacific Fleet forces under Chester W. Nimitz. Following the Battle of Midway carrier air engagements, I-168 penetrated the chaotic scene around the damaged carrier Yorktown and her escort group, which included Hammann and destroyers such as Hughes and Monaghan. Using torpedoes against the ships engaged in salvage and repair operations, I-168 fired a spread that fatally struck Yorktown and Hammann, altering the tactical outcome of the battle and influencing subsequent assessments by Fletcher and Raymond A. Spruance. Her successful attack used Mark 16 torpedo-type performance analogues and showcased submarine penetration tactics against carrier task forces noted in postwar analyses by Naval War College scholars.

Subsequent operations and final patrol

After Midway, I-168 returned to Kure for repairs and later conducted patrols in the Solomon Islands campaign, supplying Japanese garrisons and engaging Allied shipping during the Guadalcanal campaign. She operated in waters contested by units of 7th Fleet elements and Royal Australian Navy escorts, encountering aircraft from Enterprise, Hornet air groups, and Cactus Air Force squadrons based on Henderson Field. Her missions included reconnaissance for Operation RY and torpedo attacks against transports and warships, interacting with contemporaries such as I-170 and submarine tenders like Jingei. On her final war patrol she shifted to anti-shipping operations off Truk and the Bismarck Archipelago.

Loss and aftermath

I-168 was reported sunk on 4 July 1943 during anti-submarine operations by Wainwright and Ellet or by coordinated air-sea patrols using HVAR-equipped aircraft, depending on conflicting wartime reports compiled by Joint Army-Navy Assessment Committee-type postwar studies. Japanese records marked her as lost with all hands; her disappearance contributed to the attrition of the Imperial Japanese Navy submarine force, which suffered losses in operations against improved Escort destroyer tactics, Hedgehog anti-submarine weapons, and carrier-based ASW aircraft such as the Avenger and Wildcat. The loss was noted in communications within the 6th Fleet and in analyses by Allied intelligence units including Fleet Radio Unit Pacific (FRUPAC).

Wreck and legacy

The wreck of I-168 has been the subject of postwar surveys by oceanographic teams and shipwreck researchers; however, precise location and condition have been reported variably in publications by maritime historians associated with institutions like the Naval Institute Press and the National Geographic Society. I-168's legacy is preserved in studies of submarine warfare at venues such as the Naval War College, in commemorations at the Kure Maritime Museum and in memorials to IJN submariners. Her actions at Midway are frequently cited in campaign histories alongside analyses by historians such as Roberto Rafuse, Jonathan Parshall, Anthony Tully, E. B. Potter, and in documentary treatments by NHK and History Channel programs. I-168 remains a case study in planning, execution, and the risks of long-range submarine operations in the Pacific theater.

Category:Kaidai-class submarines Category:Submarines of the Imperial Japanese Navy Category:Ships built by Kure Naval Arsenal Category:World War II submarines sunk by United States warships