Green’s Dictionary of Slang

(US) a euph. for damned adj.

1798		Aurora (Phila.) 14 Aug. n.p.: It seems as if the Irish are as incorrigible as the darnation Bostonians [OED].
1807		letter in Christian Schultz Travels (1810) I 24 July 20: This was the second time ‘the darnation devil had visited them’.
1838		Blackburn Standard 16 May 4/1: You ar [sic] a darnation plaguey clever fellow.
1844		‘Jonathan Slick’ High Life in N.Y. I 174: Who’d a thought of finding one of these darnation lottery offices here!
1864		Empire (Sydney) 15 Feb. 2/3: The darnation yankee.
1867		Paisley Herald 28 Sept. 6/4: It were a durnation bit o’ folly from end to end.
1878		Bristol Mercury 4 Feb. 2: Howe we did hurry on / To the darnation stashen, vur vear the trane wur gone.
1882		Lancaster Gaz. 14 Jan. 5/4: It’s a darnation hard one.
1891		Coventry Eve. Teleg. 30 Dec. 4/3: Bucklow was excessively riled [...] and called the boatswain a darnation old woman.
1925		Exeter & Plymouth Gaz. 24 Dec. 2/1: ’Tis a case of Hobson’s choice. I wude’n wear the darnation things ef I wad’n ’bliged to.
1929		Derby Dly Teleg. 2 Feb. 7/7: I’ve brought her a trunk and I’ve filled it with stockings, hats [...] trinkets — every darnation thing.