How long has "Semper Fi" been the motto of the Marine Corps?

The U.S. Marine Corps officially adopted the motto "Semper Fidelis," often shortened to "Semper Fi," in 1883. The motto translates to "always faithful" and replaced three previous mottoes that were never official.

The first unofficial motto of the U.S. Marines was "Fortidine," or "with fortitude," which dates to prior to the War of 1812. The second unofficial motto was "By Sea and by Land," a counterpart to the Royal Marine’s "Per Mare, Per Terram." "To the Shores of Tripoli" was the third Marine motto, which was later lengthened to "From the Halls of the Montezumas to the Shores of Tripoli." England's Devonshire Regiment, the 11th Foot, also uses the motto "Semper Fidelis."