Letter Written By Feudal General Hideyoshi Discovered; Sought to Entice Enemy Retainer to Switch Sides

The Yomiuri Shimbun

13:15 JST, November 26, 2025

A letter written by feudal general Toyotomi Hideyoshi has been discovered, promising rewards to an enemy retainer if he will switch sides. Hideyoshi wrote the letter apparently unaware that his master, Oda Nobunaga, had been killed just the previous day.

Written on June 3, 1582, the letter was addressed to a samurai retainer of the Mori clan in the Chugoku region. Hideyoshi — who was known as Hashiba Hideyoshi at the time — promises such compensation as the rights to the land of Bingo in what is now Hiroshima Prefecture.

The letter is noteworthy for its clarification of Hideyoshi’s political strategy at the time of the so-called Honnoji Incident, in which Nobunaga died in a conflict with Akechi Mitsuhide at the Honnoji temple on June 2 of that year.

It measures 32.8 centimeters high and 44.7 centimeters wide. It is now arranged as a hanging scroll.

Yuki Murai, an associate professor of the University of Tokyo’s Historiographical Institute, acquired the letter through an internet auction in October this year. Murai specializes in medieval Japanese history and believes that the letter is the original, as it bears Hideyoshi’s kao signature and the handwriting of his secretary.

At the time, Hideyoshi was besieging Bitchu Takamatsu Castle in what is now Okayama City as the top commander of the force attacking the Mori clan at Nobunaga’s order. The letter appears to have been written to Uehara Motosuke, a son-in-law of former clan leader Mori Motonari.

As a reward for Uehara giving his loyalty to “Ue-sama” (Lord), meaning Nobunaga, Hideyoshi pledges to get a document with a vermillion seal from Nobunaga that will give Uehara the right to govern Bingo. Should that prove impossible, the letter says, Uehara will be given a place of his choice in the land of Bitchu in what is now Okayama Prefecture.

It is believed that Hideyoshi learned of Nobunaga’s death after he sent the letter, probably sometime from the late evening of June 3 to the early morning of June 4. Hideyoshi later made peace with the Mori clan, and together they defeated Mitsuhide.

According to Murai, however, Uehara’s switching sides may have contributed to their eventual peacemaking, as he was a major retainer of the Mori clan.

“The letter shows us how Hideyoshi, who didn’t know about the death of Nobunaga, schemed to cajole an enemy with ‘big words,’ such as giving him Bingo or Bitchu. This is very important because it was sent right around the time of the Honnoji Incident,” Murai said.

The letter will be made public for the first time at a special exhibition at the Ibaraki Prefectural Archives and History Museum in Mito, from Feb. 7 next year.