The United States Coast Guard (USCG) is a branch of the United States military, founded on 28 January 1915. The Coast Guard's predecessor, the Revenue Marine, was created by the US Congress on 4 August 1790 at the request of Alexander Hamilton, and its original purpose was to collect customs duties in the nation's seaports. By the 1860s, the service became known as the Revenue Cutter Service, and the Revenue Cutter Service and the Life-Saving Service merged to form the Coast Guard in 1915. During World War I and World War II, the Coast Guard was transferred to the Department of the Navy, protecting American territorial waters from German U-boats. In 2018, the USCG had a strength of 40,992 active duty personnel, 7,000 reservists, 31,000 auxiliarists, and 8,577 civilian employees. It also had a fleet of 243 coastal and ocean-going patrol ships, tenders, tugs, and icebreakers called "cutters", and 1,650 smaller boats.