garrison hack, n. — Green’s Dictionary of Slang

garrison hack n.

[ironic use of SE garrison hack, a regular attender at military balls. Such a woman, like the horse, can be ‘ridden’ by anyone]

a prostitute.

[1853		Delhi Sketch Bk 1 Nov. 81/2: He can do a hawker, bully a company, flirt with a garrison ha! I mean a young lady at a ball].
1867		London Standard 14 Jan. 3/7: The ‘Garrison Hack’ is a serio-comic story of hunting for a husband, and it ought to be read attentively by young ladies [in] the Indian matrimonial market.
1870		Graphic (London) 20 Aug. 11/3: Some girls have carried on to such an extent as to gain the name of ‘Garrison Hacks’.
1875		Leeds Times 27 Mar. 6/5: She was then what is termed in the vulgar tongue, a garrison hack.
1880		Manchester Courier 25 Sept. 14/3: The men go off in a pack / To dangle about some chit just ‘out’ — / Who smirks like a garrison hackl.
1890		Athenaeum 8 Feb. 176/1: The heroine is a ‘garrison-hack’.
1893		Hartlepool Mail 2 Mar. 4/6: ‘Mark my words, Angy [...] your flirting ways will bring you into trouble. You will [be] a regular garrison hack.’ [...] ‘Oh, Tom’ how can you be so vulgar!’.
1900		Wrexham Advertiser 7 June 2/5: When Baden-Powell was quartered at Malta, he was pestered with the attentions odf a lively girl who answered to the description of ‘a garrison hack’.