There had long been a rivalry between the families of Percy and Douglas, which showed itself by incessant raids into each other's territory. Percy of Northumberland one day vowed he would hunt for three days in the Scottish border, without condescending to ask leave of Earl Douglas. The Scotch warden said in his anger, “Tell this vaunter he shall find one day more than sufficient.” The ballad called Chevy Chase mixes up this hunt with the battle of Otterburn, which, Dr. Percy justly observes, was “a very different event.”
(Chaucer, chevachie, a military expedition on horseback.)
To louder strains he raised his voice, to tell What woful wars in `Chevy Chase' befell, When Percy drove the deer with hound and horn, Wars to be wept by children yet unborn.
Gay: Pastoral VI.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894