For example, in 1793, the McCartney Mission tried to get better trade conditions with China and was a total failure. Here's the Qianlong Emperor's well-known response to the British. Hitherto, all European nations, including your own country's barbarian merchants, have carried on their trade with our celestial empire at Canton. Such has been the procedure for many years, although our celestial empire possesses all things in prolific abundance and lacks no product within its own borders. But then Europeans, especially the British, found something that the Chinese would buy. Opium. By the 1830s, British free trade policy unleashed a flood of opium in China, which threatened China's favorable balance of trade.