The Treaty of Nanking ended what hostile event between the Chinese and the British?

It ended the first Opium War between Great Britain and the Qing Dynasty in China. The name ascribed to the war is misleading. It appears superficially to be an effort to reverse China's policy of halting the illicit trade to China of opium that was pursued by the East India Company. Tthe actual agenda was to resolve the foreign trade deficit the British were suffering because of very tight restrictions the Qing enforced on British trade with China.

Unsurprisingly, the British won, and as part of the settlement the Qing were forced to expand the number of ports of entry for British commerce as well as conceding Hong Kong to Britain as a crucial beachhead on the Chinese mainland so they could better pursue their lucrative Asian trade.