This chapter’s premise is to take synchrony seriously, to think that comovements in apparently separated places and social domains may reveal unexpected unities. The focus is 1866, the year of the “Summer War” that began the overthrow of the Tokugawa shogunate. The chapter’s first theme is the revolution in prices. The great inflation of the 1860s is the most striking event in Japan’s nineteenth-century price history. Its extreme point came in 1866. Inflation connects to a second theme, the international boom and bust of the 1860s. Japan joined the world trading system at a time of surging commodity prices. When prices collapsed internationally in 1865–66, it set off credit panics from Bombay to London to Shanghai. Food prices soared, connecting to a third theme, of harvest crises and popular uprisings. Weather anomalies across Eurasia included droughts associated with a strong El Niño, and cold wet weather that ruined harvests in Europe. Japan’s 1866 rice harvest was the worst since the famines of the 1830s; 1866 also set an Edo period record for popular uprisings. From international finance to food provision to the remaking of political regimes, it was a watershed time; a story that is both Japanese and international.