240 Years and counting!
On November 10, 1775, the Second Continental Congress meeting in Philadelphia passed a resolution stating that "two Battalions of Marines be raised" for service as landing forces with the fleet. This resolution established the Continental Marines and marked the birth date of the United States Marine Corps. Serving on land and at sea, these first Marines distinguished themselves in a number of important operations, including their first amphibious raid into the Bahamas in March 1776, under the command of Captain (later Major) Samuel Nicholas.
The first commissioned officer in the Continental Marines, Nicholas remained the senior Marine officer throughout the American Revolution and is considered to be the first Marine Commandant. The Treaty of Paris in April 1783 brought an end to the Revolutionary War and as the last of the Navy's ships were sold, the Continental Navy and Marines went out of existence.
Read more about the history of the Marine Corp at Military.com