After the prolonged civil war of the Sengoku Jidai, or Warring States period, peace reigned over Japan for 200 years. In Kyoto, the Emperor continued as divine head of state. But real power was held by the Tokugawa shogunate. For two centuries, they ruled with absolute authority. Japan prospered, the people were content. In 1854 American warships changed everything. The Shogun welcomed the west, and signed a treaty of peace and amity. The gates to Japan were open. Trade was established, but the agreements favoured the western powers. The economy faltered and the people suffered. In 1863, the Emperor overruled the shogun, and an Imperial decree ordered the expulsion of all western powers.
This led to a conflict between forces still loyal to the shogun and those who supported the emperor’s decision, and a war broke out over the future of Japan.