Green’s Dictionary of Slang

(US milit.) to imprison.

1920		in Amer. Legion Weekly 20 Aug. 13: Don’t you know [the M.P.’s] motto? ‘Brig ’em young!’ [HDAS].
1931		Irwin Amer. Tramp and Und. Sl. 37: brig.–To imprison or confine.
1953		L. Uris Battle Cry (1964) 179: You guys get in here before the Shore Patrol brigs you all.