I-168

I-168 was a Kaidai-class submarine built for the Imperial Japanese Navy and commissioned shortly before the Pacific War. Serving in the Combined Fleet and attached to various submarine squadrons, she operated in the Indian Ocean, off Hawaii, and in the Solomon Islands and New Guinea theaters. The boat is most noted for a single decisive action against the United States Navy task force following the Attack on Pearl Harbor and for her subsequent loss during intensified Battle of the Philippine Sea operations.

Design and specifications

The submarine was laid down and constructed by Mitsubishi Heavy Industries at the Kawasaki shipyard as part of the Kaidai development intended to improve range and surface speed for long-distance operations alongside surface units such as the Kido Butai carrier striking force. I-168 belonged to the KD6A sub-class, featuring diesel-electric propulsion derived from designs influenced by earlier Kawasaki and Yokosuka prototypes. Displacement, surfaced and submerged, reflected the requirements for extended patrols across the Central Pacific and Indian Ocean; endurance and fuel capacity were optimized to support operations from bases such as Truk and Rabaul. Her armament complemented torpedo loads compatible with the Type 95 torpedo and deck guns employed against merchant shipping near chokepoints like the Makassar Strait and Coral Sea lanes. Sensor fit included hydrophones and early periscopes used for reconnaissance tasks supporting carrier groups such as the 1st Air Fleet during major operations including Operation MO and the Midway area deployments.

Service history

After commissioning, the vessel joined training and patrol assignments under the Combined Fleet's submarine command, moving between forward bases at Kwajalein, Truk Lagoon, and Rabaul. Her operational tempo increased as the Imperial Japanese Navy sought to interdict Allied supply routes and challenge United States Navy carrier task forces. I-168 operated alongside contemporaries from Submarine Squadron 3 and coordinated with surface units like the Kongō-class battleships and carrier divisions that executed the attack on Pearl Harbor and subsequent raids across the Pacific Ocean. Patrols focused on both offensive sorties against warships and commerce raiding in support of broader campaigns—interacting with major events such as the Indian Ocean raid and the Solomon Islands campaign.

Notable patrols and engagements

The submarine's most famous patrol occurred in the immediate aftermath of the Battle of Midway, when she penetrated the perimeter of the U.S. Navy carrier screen tasked with recovering damaged ships and rescuing survivors. During this patrol she launched torpedoes that struck and sank multiple American vessels, including the fleet oiler USS Yorktown (CV-5) and damaging the destroyer USS Hammann (DD-412), actions that influenced post-battle salvage and withdrawal decisions by Admiral Chester W. Nimitz's forces. Other patrols brought her into contact with convoys and task groups near New Guinea and the Solomon Islands where she engaged Allied merchant shipping and escorted convoys routed from Australia and New Caledonia; in those operations she drew on intelligence coordinated with Naval General Staff directives and local commanders such as those based at Rabaul and Truk. The boat’s successful torpedo attacks showcased employment of the Type 95 torpedo against both auxiliary and combatant vessels, and her actions were referenced in post-action reports by units including Task Force 16 and carrier air groups such as those from USS Enterprise (CV-6).

Loss and aftermath

I-168 was lost in 1943 during operations in a period when Allied anti-submarine warfare capabilities—employing assets such as Escort Carriers, destroyer escorts like USS Radford (DD-446), and aircraft including PBY Catalina patrol planes—were intensifying across the Southwest Pacific. Her sinking followed coordinated ASW efforts informed by signals intelligence efforts akin to work by Station HYPO and improved sonar tactics used by Allied navies. The loss contributed to the attrition of the Imperial Japanese Navy submarine force that struggled to replace trained crews and modern sensor systems while contending with expanding Allied logistics protections and escort doctrine. Survivors and casualty lists were recorded by fleet commands and later assessed in post-war analyses by naval historians and commissions.

Wreck and legacy

The wreck of the submarine remained undisturbed for decades, with occasional expeditions by maritime archaeologists, deep-submergence teams, and private researchers from institutions such as university marine labs and organizations involved in shipwreck exploration. Its remains contribute to the study of naval architecture of interwar Japanese submarines and the evolution of torpedo damage patterns relevant to both U.S. Navy and Imperial Japanese Navy studies. Commemorations at memorials in locations like Pearl Harbor and regional museums in Rabaul and Yokosuka reference the broader submarine war rather than single ships, and the boat's action at the Midway aftermath remains cited in analyses by naval historians, war colleges, and authors documenting the shifting balance in underwater warfare during the Pacific Theater.

Category:Kaidai-class submarines Category:Imperial Japanese Navy submarines