The Yangtze Patrol, also known as the Yangtze River Patrol Force, Yangtze River Patrol, YangPat and ComYangPat, was a prolonged naval operation from 1854–1949 to protect American interests in the Yangtze River's treaty ports. The Yangtze Patrol also patrolled the coastal waters of China where they protected U.S. citizens, their property, and Christian missionaries. The Yangtze River is the longest river in China and it plays an important commercial role, with ocean-bound vessels proceeding as far upstream as the city of Wuhan. This squadron-sized unit cruised the waters of the Yangtze from Shanghai on the Pacific Ocean into the far interior of China at Chungking. Initially, the Yangtze Patrol was formed from ships of the United States Navy and assigned to the East India Squadron. In 1868, patrol duties were carried out by the Asiatic Squadron of the United States Navy. Under the unequal treaties, the United States, Japan, and various European powers, especially the United Kingdom, which had been on the Yangtze since 1897, were allowed to cruise China's rivers. In 1902, the United States Asiatic Fleet took control of the operations of the Yangtze Patrol. In 1922, Yangtze Patrol was established as a formal component of the United States Navy in China. In 1942, at the beginning of World War II, the Yangtze Patrol effectively ceased operations in China because of the limited resources of the United States Navy, which needed the patrol crews and their ships elsewhere in fighting Japanese forces throughout the Pacific. Following the end of World War II, the Yangtze Patrol resumed its duties in 1945, but on a more limited basis with fewer ships during the Chinese Civil War. When the Chinese Communist forces eventually occupied the Yangtze River valley in 1949, the United States Navy permanently ceased operations and disbanded the Yangtze Patrol. Operations (1854–1949) 19th century 1854–1860 As a result of treaties imposed on China by foreign powers after the First (18391842) and Second Opium Wars (18561860), China was opened to foreign trade at a number of locations known as "treaty ports" where foreigners were permitted to live and conduct business. Also, created by the treaties was the doctrine of extraterritoriality, a system whereby citizens of foreign countries living in China were subject to the laws of their home country. Most favoured nation treatment under the treaties assured other countries of the fact that the same privileges would be afforded to