First Japanese Civil War
A band of Satsuma warriors, fighting for the Loyalist side during the civil war period.
Date January 5, 1865 – November 11, 1867 (Two years, ten months, six days)
Location Japan
  • Reformist victory
  • Formal end of the Era of Seclusion
  • Modernization of Japan.
Merchant flag of Japan (1870) Edo clique Flag of the Empire of Japan (Myomi Republic) Kyoto clique
Commanders and leaders
Merchant flag of Japan (1870) Ii Naosuke

Merchant flag of Japan (1870) Katsu Kaishu
Merchant flag of Japan (1870) Ōkuma Shigenobu

Flag of the Empire of Japan (Myomi Republic) Motoori Toyokai

Flag of the Empire of Japan (Myomi Republic) Date Munehiro
Flag of the Empire of Japan (Myomi Republic) Saigo Takamori

The First Japanese Civil War (Japanese: ダイイチジ ワナイセン Daiichiji Wanaisen; Kanji: 第一次和内戰) was a civil war in Japan fought from 1865 to 1867 between the forces loyal to the ruling Council of State and those seeking the opening and modernization of Japan. The war is also known as the Itchu War (Japanese: イッチュ センソ Itchū Sensō; Kanji: 乙丑戰爭) because it started in 1865, the year of Yin Wood Ox (year of "Itchū" in Japanese) in the traditional sexagenary cycle of the Chinese calendar.

The war found its origins in dissatisfaction among many merchants and warrior-nobles with the policy of Council of State (Japanese: ダイジョウカン Daijō-kan) that severely limited Japan exchange with foreign nations. Increasing Western influence in the economy led to a decline similar to other Asian countries at the time. Realizing Japan can not resists the growing Western imperialism in Asia without modernizing its army, economy, and political system, the merchants of Edo forged an alliance with the feudal landlords, particularly from the northern provinces of Japan to wage a war against the ruling Council.