Another weekend, another great British city: Edinburgh, one of my favourite places. It is getting ready for the upcoming Festival and, amongst many cultural highlights, its famous military tattoo. I was intrigued by this word, so of course I looked it up:

“signal,” 1688, “signal calling soldiers or sailors to quarters at night,” earlier tap-to (1644, in order of Col. Hutchinson to garrison of Nottingham), from Du. taptoe, from tap “faucet of a cask” + toe “shut.” So called because police used to visit taverns in the evening to shut off the taps of casks. Transf. sense of “drumbeat” is recorded from 1755.

etymonline

So a drummer accompanied with an officer calling “close the bar” (doe de tap toe) would signal to innkeepers that they had to stop serving drinks and close the barrels so the soldiers would go back to the barracks. This practice spread to England through William of Orange and then to armies with Anglo-Saxon traditions. In France, the retraite aux flambeaux, although it has lost its military connotations, apparently has similar origins, but I couldn’t find any information on the subject.