Green’s Dictionary of Slang

1. (US) a white Southerner, orig. spec. a fighter for the Confederacy; also used as a nickname or term of address.

1862		G.W. Whitman in Civil War Letters 8 Dec. 74: The Rebs are posted on the opposite bank.
1865		G.A. Sala My Diary in America I 235: A regiment of ‘Confeds’ – who are this year called ‘Johnnies:’ they were ‘Rebs’ in 1861, and ‘Greybacks’ in 1862.
1872		‘The Last Rebel Yell’ in Farmer of Chappaqua Songster 17: I’m a rale old Reb, with but one left leg.
1895		S. Crane Red Badge of Courage (1964) 98: We’ll be at th’ rebs in less’n an hour.
1902		J.A. Riis Battle with the Slum 336: The Twenty-third Illinois Volunteers had battled with the Rebs weary nights and days.
1904		O. Kildare Good of the Wicked 29: ‘Reb’ Carlisle was reciting the battle of Winchester in installments.
1909		‘O. Henry’ Roads of Destiny 350: That’s why you see me cake-walking with the ex-rebs to the illegitimate tune about ’simmon-seeds and cotton.
1911		‘Sing Sing No. 57,700’ My View on Books in N.Y. Times Mag. 21 May 7/5: This Colonel Carter is an old Reb who is strong on the eats.
1926		(con. 1860s) F.J. Wilstach Wild Bill Hickok 45: M’Kandlas and his gang were border ruffians in the Kansas row, and, of course, they went with the rebs.
1940		F. Hunt Long Trail from Texas 131: Shut up reb, an’ get movin’ afore I fergit myself.
1965		(con. 1944) E.M. Nathanson Dirty Dozen (2002) 77: Gordon would bet anything he was a Reb.
1968		(con. c.1900) J. Thompson King Blood (1989) 82: Ain’t hardly no one in the Territory that ain’t a reb.
1971		I. Faust Willy Remembers 66: ‘The Virginian.’ ‘Heckyes, I read that. It is all about a reb in the Wild West.’.
1978		Maledicta II:1+2 (Summer/Winter) 168: Reb Same as Johnny Reb.
2000		G.V. Higgins At End of Day (2001) 129: Treehouses and forts [...] I assume you Rebs had them too.

2. attrib. use of sense 1.

1899		F.E. Daniel Recollections of a Rebel Surgeon 51: I could tell every ‘reb’ sympathizer in the bunch.
c.1930		(ref. to 1868) N. Kimball Amer. Madam (1981) 50: There was talk of reb raiders and the darkies cutting throats.