The Treaty of Nanking that ended the First Opium War between Britain and China in 1842 granted trading concessions in Shanghai to the European powers. The international currents shaping the city over the next hundred years were complex: British merchants, Chinese warlords, Russian emigrš, Sephardic Jews, and German spies exploited its extraterritorial status to make Shanghai a hotbed of greed, vice, and intrigue. Opium was crucial to the city's extraordinary wealth and lawlessness, though Dong also relates the rise of its criminal gangs to the development of coastal steamships and consequent loss of inland-transportation jobs. Foreign participation in the opium trade was not confined to the British: the role of the French Concession in Shanghai is described in well-researched detail. The flamboyant personalities that prospered in the city's unfettered environment come alive, characters like Pockmarked Huang, who combined the post of police chief in the French Concession with leadership of the Green Gang. Dong explores Shanghai's political significance both as the source of Chiang Kai-shek's fortunes and as a center of Communist revolutionary activity. As the city again becomes the leading commercial metropolis of a dynamic national economy, Shanghai 1842-1949 successfully documents its unique role in the development of modern China.