Second Chōshū expedition

Second Chōshū expedition; 第二次長州征討
	Part of Bakumatsu Conflicts
	; Operations map of the Second Chōshū expedition.
Date	7 June 1866
Location	Western Japan
Result	Chōshū victory
Belligerents
Chōshū Domain	Tokugawa shogunate; Aizu Domain; Fukuyama Domain; Hamada Domain; Higo Domain; Hikone Domain; Iyo-Matsuyama Domain; Karatsu Domain; Kishū Domain; Kokura Domain; Kurume Domain; Kuwana Domain; Ōgaki Domain; Nakatsu Domain; Takada Domain; Yanagawa Domain;
Strength
3,500–4,000	100,000–150,000
Casualties and losses
261 killed	Significant

The Second Chōshū expedition (Japanese: 第二次長州征討), also called the Summer War, was a punitive expedition led by the Tokugawa shogunate against the Chōshū Domain. It followed the First Chōshū expedition of 1864.