Toyama Maru

In 1944, Toyama Maru was sunk in one of the largest maritime losses of Japanese military personnel in the Pacific War. A Japanese passenger-cargo vessel converted to wartime transport service, it sailed south from Kagoshima in late June carrying men of the 44th Independent Mixed Brigade bound for Okinawa and the Ryukyus. On 29 June 1944, in the Nansei Shoto near Taira Jima, the ship was torpedoed by the American submarine USS Sturgeon and sank with catastrophic loss of life. Public sources consistently describe the sinking as one of the worst maritime disasters of the war, with only a few hundred survivors out of more than 6,000 men aboard.

The Ship

Toyama Maru was a Japanese passenger-cargo ship of 7,089 tons later used in wartime transport service. The U.S. Naval History and Heritage Command’s merchant-shipping loss list identifies it as a passenger-cargo vessel, while CombinedFleet’s tabular record traces its wartime movements as a transport. By mid-1944 it was being used to move large troop drafts southward as Japan attempted to reinforce threatened island positions.

The Voyage

CombinedFleet records that Toyama Maru departed Moji on 18 June 1944 for Kagoshima, carrying men of the 44th Independent Mixed Brigade, and then departed Kagoshima on 27 June 1944 for Naha in the Ryukyus. The ship was part of a southbound military reinforcement movement at a time when American submarines were inflicting increasingly heavy losses on Japanese shipping. Publicly accessible sources for this final voyage emphasize the transport of Japanese troops rather than a documented large Allied POW draft aboard the ship at the time of sinking.

The Attack or Loss

On 29 June 1944, USS Sturgeon torpedoed Toyama Maru in the Nansei Shoto, near Taira Jima. CombinedFleet and the U.S. Naval History and Heritage Command both record the sinking on that date, with NHHC listing the loss position at approximately 27-41N, 129-09E. Public summaries agree that the ship went down with devastating speed and loss of life. Because the ship was operating as a military transport, it was a legitimate wartime target for American submarines.

Casualties and Survivors

The public casualty totals are broadly consistent. CombinedFleet states that 5,400 troops of the 44th Independent Mixed Brigade were lost, while other summaries describe over 6,000 men aboard with only about 600 survivors. The exact totals vary depending on whether the source counts only troops or all persons aboard, but all agree that Toyama Maru was one of the worst Japanese maritime losses of the war.

Legacy and Memorialization

Toyama Maru is historically significant because it reflects the scale of Japanese shipping losses in 1944 and the growing effectiveness of Allied submarine warfare against Japan’s reinforcement routes. The Toyama Maru may be relevant to the wider wartime transport context, but the open-access sources reviewed here support it most strongly as a major troop transport loss, not as one of the core POW-casualty Hellship disasters. That distinction matters for accuracy and for maintaining the credibility of our website.

Sources

CombinedFleet, IJA TOYAMA MARU: Tabular Record of Movement.
U.S. Naval History and Heritage Command, Japanese Naval and Merchant Shipping Losses – WWII.
Additional public summaries of the sinking, useful for context but less authoritative than the above.

Tamahoko Maru
Kōshū Maru
Jun’yō Maru
Hellships Research Center
Hellships Researcher Guide