Who was Motochika?
Chosokabe Motochika (1539–1599) unified the whole island of Shikoku from a base in Tosa Province — modern Kochi — completing the conquest in 1585. Within months Toyotomi Hideyoshi invaded with an overwhelming force and reduced him to his home province again.
He is known for building an army out of the ichiryo gusoku, part-time warriors who farmed with their weapons beside them and could be called up at short notice. It was a cheap system suited to a poor province, and it worked until it met a national army.
Why is Motochika important?
- He unified Shikoku, one of Japan's four main islands, in roughly twenty years of campaigning.
- His militia system is a well-documented example of how a poor domain generated military power.
- The Chosokabe Motochika Hyakkajo, a hundred-article household code issued in 1597, is an important source for Sengoku domain law.
- The destruction of his house after 1600 shaped the politics of Tosa, which later produced key figures of the Meiji Restoration.
From Tosa outward
Motochika was reportedly so pale and quiet as a young man that retainers doubted he could lead; his first battle in 1560 ended the doubts. He spent the next two decades absorbing rival houses in Tosa and then pushing into Awa, Sanuki and Iyo.
He had been negotiating with Oda Nobunaga, but relations broke down and an Oda invasion of Shikoku was being prepared when Nobunaga was killed at Honnoji Incident in 1582. Some historians argue that this pending invasion is connected to Akechi Mitsuhide's motive.
Submission and decline
Hideyoshi invaded Shikoku in 1585 with a large army under several commanders. Motochika submitted after a short campaign and was allowed to keep Tosa alone.
In 1586 he served in the Kyushu campaign, where his eldest son and designated heir Nobuchika was killed at Hetsugigawa. Accounts describe Motochika as never recovering from it, and the succession disputes that followed weakened the house badly.
After his death
His son Morichika joined the Western Army in 1600, was stationed where he could not fight effectively at Battle of Sekigahara, and lost everything. Tosa was given to Yamauchi Kazutoyo.
Morichika later joined the defenders at the Siege of Osaka and was executed after its fall. The Chosokabe ended there as a daimyo house.
Legacy
The friction between the incoming Yamauchi retainers and the displaced Chosokabe warriors persisted for generations in Tosa, and is often cited as background to the radical politics that came out of the domain in the 1860s.
Kochi maintains the ruins of his castles and a substantial local memory of him as the province's own lord.
