Green’s Dictionary of Slang

(US) hellish, damnable, thus tarnationest, worst possible.

1784		W. Wilson in Memoirs (1896) 47: They only came to look at the ‘tarnation Tories’ from Canada [OED].
c.1815		J.K. Paulding Bucktails (1847) II ii: Run as if heaven and earth were coming together, for he’s in a tarnashun haste.
1827		T. Hood ‘A Sailor’s Apology for Bow-legs’ Works (1862) I 320: And there’s my timbers straining [...] And her tarnation hull a-growing rounder.
1828		Arkansas Gaz. (AR) 15 Jan. 1/5: There’s a tarnation great pot boiling all the time.
1831		Satirist (London) 8 May 35/2: The Peers (to believe it I scarcely know how) / Heigho! says Billy. / Were just kicking up a tarnation row.
1837		R.M. Bird Nick of the Woods I 185: I’ve beat you, you tarnation, scalping varmints!
1838		Crim.-Con. Gaz. 27 Oct. 79/3: Missey crow wake me wid a tarnation kick.
1843		R.S. Surtees Handley Cross (1854) 334: That tarnation fox has been at the (puff) poultry again.
1843		Satirist & Sporting Chron. (Sydney) 18 Feb. 3/2: What has become of the sporting Major? It is generally supposed that the Gordian knight has got him into such a ‘tarnation fix’ that he can’t show.
1849		W.C. Hall ‘Mike Hooter’s Fight with the “Bar”’ Spirit of the Times 10 Nov. (N.Y.) 452: He was the most tarnationest, rampagin bar ever you see.
1856		C. Reade It Is Never Too Late to Mend III 222: The tarnation hypocrite.
1870		Barnsley Chron. 26 Mar. 6/2: ‘I’d have gin him the tarnationest lickin he ever got in his born days’.
1872		Bloomfield Times (PA) 22 Oct. 3/2: I’ve got tarnation toothache [...] the tarnal thing’s been aching for nigh four weeks.
1884		Ally Sloper’s Half Holiday 10 May11/1: I said the whole tarnation yarn / Was one tarnation whopper!
1887		G. Davis Recoll. Sea-Wanderer 331: ’Tis astonishing what tarnation fools old widowers will make of themselves, anyhow.
1897		Wash. Post 9 May 27: There was a bruise over one eye where his head has struck against a fragment of Pike’s Peak, one elbow felt ‘like a tarnation wildcat had clawed it’, and there was a general feeling of soreness.
1909		Gem 6 Feb. 23: Screw yourself into the tarnation earth!
1916		Sun. Times (Perth) 24 Dec. 2s/4: He was a little tin-god at that tarnation camp.