Among the lesser publicized tales of World War II, few are as haunting—or as captivating—as the abrupt disappearance of Japan’s battleship Mutsu. A former landmark icon of naval superiority and national pride, its loss in 1943 begged a litany of questions and ranks as one of the most enigmatic pages in Japanese sea history.
Mutsu was developed from the ambitious Eight-Eight Fleet Plan of the Imperial Japanese Navy, an earlier plan to construct a fleet strong enough to rival world powers. The Nagato-class battleships were developed from this plan, and Mutsu was the second ship of this class. She was commissioned in 1921, when Crown Prince Hirohito and his mother attended the ceremony. Partially funded by public donations, the ship was filled with national pride. While Japan was negotiating the Washington Naval Treaty, Mutsu was spared from being dismantled in favor of other ships and cemented her symbolic status.
Mutsu was state-of-the-art when she was first introduced. Stefan Draminski, a military historian, explains that the Nagato-class was the first to have 16-inch guns, which was symptomatic of Japan’s preference for quality rather than quantity. During the 1930s, armor upgrades were added to the ship in the form of propulsion and a pagoda-type mast. By the start of World War II, she was still a force to be reckoned with, though the entry into service of Yamato-class super-battleships later overwhelmed her power.
Although capable, Mutsu was kept somewhat out of line combat. She served operations away from range during the Pearl Harbor raid, served as a training ship, and aided Yamato in several drills. She went to the Battle of Midway but didn’t fire, and she had only one real fight at the Battle of the Eastern Solomons, where she strafed American reconnaissance aircraft. For much of the war, she acted as a training and transport ship—a giant vessel whose function increasingly diminished. It all came crashing down on June 8, 1943. In Hashirajima Bay, Mutsu carried over 100 naval cadets and 40 instructors on a tour.
A huge explosion ripped through the area under her No. 3 turret at 12:13 p.m., ripping the ship in two. The bow half sank rapidly, and the stern portion was charred and afloat before finally sinking after several hours. Of the 1,474 aboard, only 353 were saved, plus 13 of the cadets. The disaster stunned the Imperial Navy and the nation to its core.
Secrecy and panic accompanied it. Anti-submarine patrols were dispatched, but the attacking foe was not found. To maintain morale, the incident was covered up, survivors were rerouted, and families of missing personnel were not told for months.
In one particularly tragic instance, the captain’s wife of Mutsu, Teruhiko Miyoshi, is said not to have learned of her husband’s demise until January 1944, igh on seven months later. The cause of the blast soon gave rise to rumors.
The ship’s Type 3 “Sanshikidan” shells were first suspected, notoriously, as they were unstable. Red or brown smoke was observed by witnesses rather than white from expected shell explosions. The Navy eventually blamed the explosion on sabotage by one of the seamen scheduled to be court-martialed that morning. Everyone scoffed at this explanation, including the fact that the sailor’s body had not been recovered during the first salvage attempt, and that he was used as a convenient scapegoat.
Other speculations include an internal collision. Even after improvements, Mutsu carried enormous amounts of combustible material and retained old electrical systems. A faulty electrical circuit or stray spark might have started a fire that had spread to the magazine. With a Navy already tottering in the Pacific, such a concession would have been disastrous.
Years passed by, and the reality continued to elude everyone. Salvage efforts continued for decades, but artifacts like her crest and a turret were salvaged. Remains of the lost sailor were discovered in 1970, yet Mutsu’s destiny continued to be a mystery.
Today, the Mutsu Memorial Museum honors the lives lost and serves as a reminder of the consequences of pride, secrecy, and human error combined with catastrophic outcomes. Whatever the explosion was caused by, whether it was sabotage, accident, or caused by careless defects, the story of Mutsu continues to haunt as one of Japan’s most tragic and mysterious naval tales.
