Green’s Dictionary of Slang

a warning cry, orig. indicating that a bailiff or constable is approaching; thus war-hawk n., a bailiff.

1626		Jonson Staple of News V ii: See! the whole covey is scatter’d; ’Ware, ’ware the hawks!
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Ware hawk; the word to look sharp, a bye-word when a bailiff passes.
1796		Sporting Mag. Aug. VIII 252/2: Remember that your country is at war, and if you do not ‘war [sic] hawk,’ you will find yourselves in the suds.
1811		Lex. Balatronicum [as cit. 1785].
1815		(con. 18C) W. Scott Guy Mannering (1999) 18: On the light [...] being observed, a halloo from the vessel, of ‘Ware hawk! Douse the glim!’.
1821		‘A Real Paddy’ Real Life in Ireland 221: They were roused by a universal shout of – war hawk, war hawk – which shook the prison walls down.
1840		Reading Mercury 30 May 3/4: I do not say that [...] but I do say to the rate-payers, for want of a more appropriate expression, ware hawk!
1849		Western Times 6 Oct. 5/4: But once let them establish their intolerant system, and ‘ware hawk!’.
1855		Bell’s Life in Sydney 2 June 3/2: Exit the schoolmaster, flourishing his shillelagh — war hawk! to the boy who hasn’t conned his lesson.
1859		‘Scene in a London Flash-Panny’ Matsell Vocabulum 102: Warehawk, then, and follow.
1879		Western Times 5 Sept. 2/3: What ho there! Ware hawk! by Jack Russell look out [etc.].
1866		J. Greenwood Little Ragamuffin 89: Jim will find her out one day, and then war-hawks to her. [Ibid.] 169: You’re a orphan, ain’t you […] Then war’orks to you!
1881		Worcs. Chron. 12 Feb. 5/2: We should say ‘ware hawk.’ Look with a suspicious eye on gold companies.
1891		Western Times 27 May 5: When it is propsed to do something to give the toiling class a lift — then ‘ware hawk’.
1895		Truth (Sydney) 12 May 1/6: The incident may, perhaps be intended [...] to convey the admonition of ‘Ware hawk’.
1906		A.H. Lewis Confessions of a Detective 203: ‘Stubble the gab!’ whispered the brute-faced creature who sat across-table from the garrulous yeggman; ‘stubble, and ware the bull!’.
1909		Exeter & Plymouth Gaz. 2 Oct. 2/4: ‘On Guard!’ ‘Ware Hawk!’ These must be the watchwords of the Conservative party.
1909		J. Ware Passing Eng. of the Victorian Era 259/1: Warrocks! (American – passing to Eng.) Beware!
1997		Share Slanguage.