(Noah's comment: When I joined the Marine Corps in the early '40s, we could not wear the emblem until we successfully graduated from boot-camp. We were not called Marine until we earned the emblem. The DI called us other things while in boot-camp, but not Marine. The commissioned officers are also happy to be referred to as Marine.)
The Eagle, Globe, and Anchor is the official emblem of the United States Marine Corps. The current emblem traces its roots in the designs and ornaments of the early Continental Marines as well as the British Royal Marines. The present emblem, adopted in 1966, differs only by a change in the eagle from the emblem of 1868. Before that time many devices, ornaments, and distinguishing marks followed one another as official badges of the Corps.
In 1776, the device consisted of a "fouled anchor" of silver or pewter. (A fouled anchor is an anchor which has one or more turns of the chain around it). The fouled anchor still forms a part of the emblem today. Changes were made in 1798, 1821, and 1824. In 1834, it was prescribed that a brass eagle be worn on the hat, the eagle to measure 3 ½ inches from wingtip to wingtip. This early insignia is found on the buttons of Marine dress and service uniforms today.
During the early years numerous distinguishing marks were prescribed, including "black cockades," "scarlet plumes," and "yellow bands and tassels." In 1859 the origin of the present color scheme for the officer's dress uniform ornaments appeared on an elaborate device of solid white metal and yellow metal. The design included a United States shield, half wreath, a bugle, and the letter "M."
The emblem recommended by the 1868 board consisted of a globe (showing the Western Hemisphere) intersected by a fouled anchor, and surmounted by a spread eagle. On the emblem itself, the device is topped by a ribbon inscribed with the Latin motto "Semper Fidelis (Always Faithful). The uniform ornaments omit the motto ribbon.