Two letters written by Adm. Isoroku Yamamoto, who led the December 1941 attack on Pearl Harbor, are being displayed in a World War II exhibit at Fukushima Museum through Sept. 15, 2025. (Fukushima Museum (private collection))

Two letters written by the head of Japan’s imperial navy during World War II are being exhibited for the first time at a museum in northeastern Japan.

The letters from Adm. Isoroku Yamamoto to his brother-in-law Toshi Mitsuhashi are on public display as part of a World War II exhibit at the Fukushima Museum in Fukushima prefecture about 180 miles northeast of Tokyo.

The Our War Experience exhibit commemorates the 80th anniversary of the war’s end in the Pacific and showcases military mail and photographs sent by soldiers to their families in the prefecture, along with uniforms and other artifacts. It runs through Sept. 15.

Yamamoto, born in Niigata on April 4, 1884, served as commander-in-chief of Japan’s combined fleet from 1939 until his death in 1943.

He led the Dec. 7, 1941, attack on Pearl Harbor, which killed more than 2,400 U.S. service members and civilians, damaged multiple ships and destroyed 188 U.S. military planes. The attack led the U.S. to declare war on Japan the next day and enter World War II.

Two letters written by Adm. Isoroku Yamamoto, who led the December 1941 attack on Pearl Harbor, are being displayed in a World War II exhibit at Fukushima Museum through Sept. 15, 2025. (Fukushima Museum (private collection))

Yamamoto was killed when a U.S. Army Air Forces Lockheed P-38 Lightning fighter shot down the Mitsubishi G4M bomber he was traveling in over Papua New Guinea on April 18, 1943.

The museum received the letters from a descendent of Yamamoto’s wife, Reiko Mitsuhashi, in July just before the exhibit opened, museum curator Ayumi Watanabe said by phone Thursday. Toshi was her younger brother.

Yamamoto “was a key figure during the Pacific war and was on the front lines,” Watanabe said. “These letters offer a glimpse into his private life and personal interactions with his family. This is a valuable resource that reveals how he viewed the attack on Pearl Harbor.”

The first letter, dated Jan. 13, 1942, was sent from the warship Nagato. Yamamoto did not wish to start a war with the U.S. but was nevertheless put in charge of Japan’s combined fleet, according to explanatory material emailed to Stars and Stripes on Wednesday along with the letters.

“As a military man close to retirement, I am engaged in an important mission,” the letter reads. “The attack on Pearl Harbor in Hawaii succeeded due to American carelessness and negligence, and the first phase of the subsequent operation [in the Nanpou region including the Philippines, Malaysia and Guam] is also progressing smoothly. However, the real battle is yet to come.”

The second letter, dated April 1942, was sent from the warship Yamato in response to an unknown previous letter from Toshi. In his response, Yamamoto expressed gratitude for Toshi’s visit to his ancestors’ grave in Wakamatsu city and wrote about his own desire to visit the grave after the war.