When it came to trade wars, the British didn't mess around. Four steam-powered battleships sent by the English to force China to change its trade policy in the mid-19th century changed the course of history. But how did they end up fighting the Chinese in the first place, and what are the contemporary echoes of this historical trade fight? Stephen Platt, the author of the recent Imperial Twilight: The Opium War and the End of China's Last Golden Age, answers these questions and more on the latest episode