On November 10, 1775, the Continental Congress issued the following decree:
That two battalions of Marines be raised consisting of one Colonel, two lieutenant-colonels, two majors and other officers, as usual in other regiments; that they consist of an equal number of privates as with other battalions, that particular care be taken that no persons be appointed to offices, or enlisted into said battalions, but such as are good seamen, or so acquainted with maritime affairs as to be able to serve for and during the present war with Great Britain and the Colonies; unless dismissed by Congress; that they be distinguished by the names of the First and Second Battalions of Marines.
So a happy 235th birthday to the US Marine Corps.
In 1921, Capt. John LeJeune issued Order 47, which said in part, ‘Since that date  many thousand men have borne the name “Marine”. In memory of them it is fitting that we who are Marines should commemorate the birthday of our corps by calling to mind the glories of its long and illustrious history.’
Thus began the tradition of the Marine Corps Birthday Ball. Here’s the way they celebrated at Quantico in 2006 – the slow march is really pretty cool: