Green’s Dictionary of Slang

a generally pej. excl. expressing anger, astonishment etc.

1650		H. Nevile Newes from the New Exchange 19: ’Tis not enough that Ladies drink, whiff, whore, / Except they swear God-dammes by the score.
1818		‘Thomas Brown’ Fudge Family in Paris Letter VIII 82: Here, Dick, arm in arm as we chattering stray, / And receive a few civil ‘God-dems’ by the way.
1822		D. Carey Life in Paris 75: There’s Wildfire Dick and Captain Flash [...] And Miss and Ma’am, / Mi Lor G-d D-mn.
1833		A. Greene Life and Adventures of Dr Dodimus Duckworth II 142: ‘Gott tam!’ exclaimed Donnervogel.
1850		W.K. Northall Life and Recollections of Yankee Hill 86: He utters more ‘Got dams’ and ‘sacré dieus‘ than would set up a whole committee of politicians for twelve months.
1901		Minneapolis Jrnl (MN) 9 Mar. 6/2: Sousa had said: ‘My band is far superior to the Grande Republique, goddamn.’ The journal went on to state that when an American wants to accentuate a statement he usually closes with goddamn.
1927		E.C.L. Adams Congaree Sketches 12: He been in old man Hall Store, an’ he say ‘God-dam’ to a nigger standin’ dere.
1938		R. Chandler ‘Red Wind’ Red Wind (1946) 49: She sighed, said, ‘Goddam,’ in a casual voice, and curled up on a davenport.
1951		M. Spillane One Lonely Night 8: Goddamn, he wouldn’t let me alone!
1961		H.S. Thompson letter 8 Dec. Proud Highway (1997) 298: God damn! Don’t you people have any boar around here?
1978		L.K. Truscott IV Dress Gray (1979) 488: ‘Goddamn-goddamn,’ said Leroy Buck.
1983		B.B. Murphy Authors Guild 23 Feb. n.p.: Goddamn in Anniston is worse than shit and bastard and son of a bitch [R].
1997		C. Hiaasen Lucky You 101: Damn. Goddamn.