During the First Opium War between Britain and China, the British captured the city in the Battle of Amoy on 26 August 1841. Xiamen was one of the five Chinese treaty ports opened by the Treaty of Nanking (1842) at the end of the war. As a result, it was an early entry point for Protestant missions in China. European settlements were concentrated on the islet of Gulangyu off the main island of Xiamen. Today, Gulangyu is known for colonial architecture and the tradition of piano-playing and organized sports.