August 4, 2015 is the 225th Birthday of the U.S. Coast Guard.
History of the U.S. Coast Guard from Wikipedia:
The roots of the Coast Guard lie in the United States Revenue Cutter Service established by Alexander Hamilton under the Department of the Treasury on 4 August 1790. The first Coast Guard station was in Newburyport, Massachusetts. Until the re-establishment of the Navy in 1798, the Revenue Cutter Service was the only naval force of the early United States. It was established to collect taxes from a brand new nation of patriot smugglers. When the officers were out at sea, they were told to crack down on piracy; and to rescue any mariners in distress.
“First Fleet” is a term occasionally used as an informal reference to the Coast Guard, although there is no indication that the United States has ever officially used this designation with reference either to the Coast Guard or any element of the Navy. The informal appellation honors the fact that between 1790 and 1798, there was no United States Navy and the cutters that were the predecessors of the Coast Guard were the only warships protecting the coast, trade, and maritime interests of the new republic.
The modern Coast Guard can be said to date to 1915, when the Revenue Cutter Service merged with the U.S. Life-Saving Service when Congress formalized the existence of the new organization. In 1939, the Lighthouse Service was brought under the Coast Guard’s purview. In 1942, the Bureau of Marine Inspection and Navigation was transferred to the Coast Guard. In 1967, the Coast Guard moved from the U.S. Department of the Treasury to the newly formed U.S. Department of Transportation, an arrangement that lasted until it was placed under the U.S. Department of Homeland Security in 2002 as part of legislation designed to more efficiently protect American interests following the terrorist attacks of 11 September 2001.
In times of war, the Coast Guard or individual components of it can operate as a service of the Department of the Navy. This arrangement has a broad historical basis, as the Coast Guard has been involved in wars as diverse as the War of 1812, the Mexican-American War, and the American Civil War, in which the cutter Harriet Lane fired the first naval shots attempting to relieve besieged Fort Sumter. The last time the Coast Guard operated as a whole within the Navy was in World War II. More often, military and combat units within the Coast Guard will operate under Navy or joint operational control while other Coast Guard units will remain under the Department of Homeland Security.
Learn more about the Coast Guard at this page which they setup for the 225th Birthday.