Lifespan: Eikyō 7 (1435) to 9/25 of Chōkyō 1 (1487) (?)
Title: Junior Fourth Rank (Upper), Assistant Vice-Minister of the Military
Bakufu: Muromachi – Commissioner of Mutsu
Father: Date Mochimune
Siblings: Kakeda Yoshimune, Shigemune, Koyanagawa Morimune, Rusu Kunimune
Wife: Egonin (daughter of Ōsaki Norikane)
Children: Hisamune, Kasai Munekiyo, Dewa-no-kami
Date Shigemune served as a bushō from the middle Muromachi to early Sengoku periods. Shigemune was the twelfth head of the Date clan of Mutsu Province.
Shigemune was born as the second son of Date Mochimune, the eleventh head of the Date family. His mother was Kentokuin.
Although Shigemune was the second son, his older brother, Date Yoshimune, was an illegitimate child so Shigemune became the designated heir. Yoshimune was adopted by Kakeda Akimune. In 1469, he succeeded his father as head of the clan. At the same time, he was appointed as the oushū-tandai, of Commissioner of Mutsu, on behalf of the Muromachi bakufu.
From 1467 to 1472, Shigemune launched attacks against the Kokubun clan on three occasions, but finally settled. Next, he attacked the Sagae clan of Dewa Province who had supported the Kokubun clan in their defense against the Date.
In the winter of 1479, Shigemune ordered Koori (Harima-no-kami) Muneyoshi to attack Sagae Castle. At this time, Sagae Tamehiro served as the twelfth head of the Sagae clan. The Sagae and Aterazawa clans were engaged in a separate dispute so the Mizonobe clan mediated a settlement evidenced by written pledges sealed in blood in the hall of the Maitreya (Bodhisattva) at the Jion Temple in Sagae. Owing to the accumulation of snowfall, Muneyoshi could not maneuver his troops as desired and, without fighting, withdrew his forces.
In the spring of 1480, after Muneyoshi launched another attack, the Sagae clan enticed them to Shōbunuma whereupon soldiers from the Mizonobe and Aterazawa clans ambushed them, causing the collapse of the Date forces. After sustaining several injuries, Muneyoshi gave-up attempts to flee and took his own life by stabbing his chest with a long sword. This event is known as the Battle of Shōbunuma.
Thereafter, Koori Munetoshi, Muneyoshi’s son and designated heir, appealed to Mogami Mitsuuji to construct the Kooriyama-Matsuzō sub-temple in a mountainous area near the Jion Temple to worship Muneyoshi and serve as the family temple.
In 1483, Shigemune traveled to the capital of Kyōto and offered gifts to the Ashikaga shōgun family including 23 long swords, 95 horses, 380 gold pieces, and 57,000 coins. This donation symbolized to the central authorities of the bakufu the unparalleled power of the Date clan in Mutsu. On this occasion, he sent horses to
He sent horses to Yukishige, the fifth-generation head of the Kanze school of nō arts and attended nō theater performed at night by a fire at the Kōfuku Temple.
In 1488, after an internal rebellion broke-out in the Ōsaki clan, Shigemune provided support to Ōsaki Yoshikane, the head of the clan, owing to the fact that his formal wife originated from the Ōsaki clan. Shigemune endeavored to restore Yoshikane to his position as head of the clan.
Shigemune’s year of death is uncertain, but, according to records of the Date family, it appears likely to have been in 1487. If this is correct, then Shigemune would not have intervened in the internal rebellion in the Ōsaki clan, and it would have been his son, Date Hisamune, instead.
Descendants of the Date clan mourned Shigemune for successive generations.