properly means to stand front to front. In savage nations opposing armies draw up front to front before they begin hostilities, and by grimaces, sounds, words, and all conceivable means, try to provoke and terrify their vis-à-vis. When this “affronting” is over, the adversaries rush against each other, and the fight begins in earnest.
A salute; a coming in front of another to salute.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894