Koshamain's War

Koshamain's War is uprising by Ainu people triggered by a murder at an blachsmith store.

Japanese suffered from this uprising, but it was eventually pacified and became the catalyst for the formation of Matsumae domain.

Background

The Ainu people, who did not have iron manufacturing technology, relied on trade in iron products and traded with the Japanese who moved into Oshima Preninsula and Ming dynasty. However, after the Tumu Crisis of 1449, when the influence of the Ming declined, trade with the Ming declined repidly, and dependence on the Japanese increased.

There was a blacksmith shop owned by a Japanese in Hakodate, Hokkaido (then called Shinosato), which was the scene of the incident. 1456, When an Ainu man tried to buy a small sword from the shop, an argument broke out over quality and price, and the blacksmith eventually stabbed the Ainu man to death with the sword. After this murder, the Ainu people united around their leader, Koshamain, and launched an attack against the Japanese in May, 1457.

Battles were fought over a wide area from Iburi to Shiribeshi, and the Ainu forces rallied at Shinosato, the site of the incident, and felled the pavilion held by Ryokei Kobayashi. The Ainu continued to advance and captured ten of the Twelve Garrisons of Southern Hokkaido, the stronghold of the Japanese, but the war ended in 1458 when Nobuhiro Takeda killed Koshamain by bow.

After the war ended, the struggle continued for a century, but in the end, the Japanese, led by Takeda, gained control. The Matsumae clan was established in Hokkaido, but two more rebellions followed.