Sakakibara Yasumasa

Sakakibara Yasumasa (1548-1606) was a military commander and daimyō from Mikawa Province (present-day Aichi Prefecture). He is renowned as one of the Four Heavenly Kings of the Tokugawa (Sakai Tadatsugu, Honda Tadakatsu, Sakakibara Yasumasa, and Ii Naomasa). Excelling in strategy, he served Tokugawa Ieyasu as a renowned commander skilled in both the military and literary arts. With Ieyasu's transfer to the Kantō in Tenshō 18 (1590), he was granted 100,000 koku at Tatebayashi in Kōzuke. As the first lord of the Tatebayashi Domain, he contributed to the governance of the Kantō.

Yasumasa was born in Tenbun 17 (1548), the second son of Sakakibara Nagamasa, a local warrior of Mikawa. From childhood he served the Matsudaira family (later the Tokugawa family) as a page and earned Ieyasu's trust. He took part in important battles, including the Battle of Anegawa in Genki 1 (1570) and the Battle of Nagashino in Tenshō 3 (1575), and built up a record of martial achievement. At Nagashino in particular, he was active as vanguard commander of the hatamoto and was known for his bravery.

In Tenshō 12 (1584), at the Battle of Komaki and Nagakute, Yasumasa fought against Hideyoshi's forces but was defeated by Hori Hidemasa and withdrew. The Hankanfu records a story that Yasumasa issued documents in various places provoking Hideyoshi's forces, so that Hideyoshi became enraged and a reward of 100,000 koku was placed on Yasumasa's head. However, this cannot be confirmed as fact and is considered a later fabrication. In Keichō 5 (1600), at the Battle of Sekigahara, he accompanied Tokugawa Hidetada's army along the Nakasendō but arrived too late for the main battle. After the war, his territory was not increased. In Keichō 11 (1606), he died at Tatebayashi Castle at the age of 59.

Yasumasa was also known as a skilled calligrapher who studied at Daijuji temple in Mikawa, and he is said to have often written letters on Ieyasu's behalf. He is highly regarded as a renowned commander who excelled in both the military and literary arts.