The Search for the Kido Butai

Frank Thompson, Deputy Assistant Director for Collection Management 
Naval History and Heritage Command

Thompson looks over historical documents and records after the discovery of IJN Akagi. Courtesy PaulAllen.com

During the first six months of the Pacific War in 1942, the Imperial Japanese Navy wielded one of the most fearsome weapons the world had ever seen: the Kido Butai – a battle group consisting of six front line aircraft carriers and their air groups, supported by an escort force of battleships, cruisers, and destroyers. As a striking force, the Kido Butai swept away opposing forces from as far away as Hawaii to Ceylon (now called Sri Lanka). Damage and aircraft losses at the Battle of Coral Sea in May rendered two carriers of the Kido Butai, Shokaku and Zuikaku, unfit for operations.

On June 4, 1942, the other four carriers of the Kido Butai- Akagi, Kaga, Soryu, and Hiryu, engaged three carriers of the United States Navy- USS Yorktown (CV-5), USS Enterprise (CV-6), and USS Hornet (CV-8) in the waters around Midway Atoll. During the battle, the aircraft from the three U.S. carriers destroyed the four Japanese carriers and won a decisive battle that proved a turning point in the Pacific Theatre of World War II. In addition to their four carriers, the Japanese also lost the heavy cruiser Mikuma. U.S. losses included the carrier Yorktown and destroyer USS Hammann (DD-412).

In 1998 and 1999, separate expeditions located the wreck of USS Yorktown and a large piece of debris believed to be from Kaga, though her wreckage remained undiscovered. During the summer of 2019, the Naval History and Heritage Command (NHHC) concluded a Memorandum of Agreement with Vulcan Inc. for the non-intrusive research of sunken military craft from the Battle of Midway. As the NHHC representative assigned to the project, I would spend the next two months aboard Vulcan’s research vessel, Petrel, working alongside an incredibly dedicated team of underwater explorers.

Prior to this mission, the Petrel team already has an impressive record of underwater discoveries to their name.  Their combination of technology and attention to historical detail resulted in the discovery of the wrecks of:

  • USS Indianapolis
  • USS Ward
  • USS Cooper
  • USS Lexington
  • USS Juneau
  • USS Helena
  • USS Hornet
  • USS Strong
  • USS Wasp
  • USS St. Lo
  • Fletcher class destroyer from Battle off Samar

On August 30, I boarded Petrel in Honolulu, casting off from the pier the next afternoon, and set course for our search area off Midway. During the transit to the search area, I interacted with the Petrel crew and the team that operates the Remotely Operated Vehicle (ROV) and the Autonomous Underwater Vehicle (AUV). Although they come from all over the globe and different backgrounds, they function as an exceptionally trained, highly professional and competent team.

When we arrived on station during the early morning hours of September 7, we were ready for the first AUV mission. Each mission lasted about thirteen hours and consisted of a run by the AUV over a search grid of five lanes. This autonomous search capability allows the initial look at large areas of ocean floor to be done by a computer that doesn’t get bored or need a break.  While the AUV worked, the team engaged in other activities ranging from equipment maintenance, administrative functions, and training. At the completion of each dive mission, the team recovered the AUV, downloaded and analyzed the data, performed maintenance, and programmed the next mission.

The first dive didn’t locate a wreck, but it did reveal large amounts of debris on the sea floor- a strong indication that we were searching in the right area. We began working methodically around that first dive grid, following the trail of debris. On Friday, September 13, the first images of a wreck appeared on the screen.

We didn’t conduct a dive on the wreck with the ROV until the evening of October 6. I felt a sense of awe as the first images of Kaga seen again after 77 years, crept across the screen. As the ROV progressed around the hull, a scene of utter destruction and devastation unfolded.

Not only were we looking at a historic shipwreck, we were also looking at the final resting place for over 800 Japanese sailors and aviators. The wreck is upright with most of the hull intact. A section of the stern is missing and believed to be in the nearby debris field. The superstructure above the main deck level including the hangars, flight deck, and island has collapsed into a twisted pile of wreckage. Upon impact with the seafloor, the bow buried itself almost up to the main deck level.

Despite the level of destruction, we did spotted key features that positively identified the Kaga– the 8-inch guns and the empty barbettes. Unfortunately, we experienced some technical problems with the ROV that cut short our dive. Repairs at sea proved impossible, and we had to limit our subsequent search to the AUV only.

We took a short break in the search to put in alongside Midway Atoll in order to conduct a press event with representatives from Vulcan Public Affairs, National Oceanic and Atmospheric Administration, Associated Press, and Lionsgate.

Picking up the search again on the morning of October 20, we discovered another wreck about 18 nautical miles east of the Kaga. With the ROV out of action, we ran a follow-up mission using higher frequency sonar on the AUV. The images it produced allowed us to confirm the discovery of the flagship of the Kido Butai, Akagi. Our time ran out before we could mount an extensive search for the other two Japanese carriers, Soryu and Hiryu. At the time of this writing, their discovery remains to be found.

A sonar image of IJN Akagi. Courtesy PaulAllen.com

My time aboard the Petrel ended on the morning of October 22. I disembarked at Midway and flew back to Honolulu for my flight home. In reviewing my notes and pictures, I recalled the importance of missions such as this one. Sea battles, unlike land battles, don’t leave visible traces on the surface. What we traditionally learn is through the study of maps, after action reports, and if available, photographs. The Petrel team conducted extensive research on the battle before we departed Honolulu. The data came from Japanese and U.S. Navy archives, as well as published accounts of the battle from academic sources. As we discovered, sometimes the information wasn’t accurate.

Historians will owe a debt of gratitude to organizations such as Vulcan and the Petrel. They’re unlocking an unseen world to us which will enable historians to “walk” around a battlefield previously off limits to us. How the history books be re-written in view of the discoveries made at Midway remains to be seen. On my way home, my mind rehashed the extraordinary events of the last two months. It ranks as one of the most profound experiences of my nearly 30 years at NHHC. With the mission over, I remembered the last two lines of John Masefield’s poem “Ships” which, perhaps, sums up the importance of the Kido Butai and the U.S. Navy ships that participated in the Battle of Midway: “They mark our passage as a race of men – Earth will not see such ships as those again.”