fourrage

Old French fourrage (fodder, forage) came from forre or fuerre (fodder, straw), possibly from Frankish fodar (fodder). Fourrager meant to forage, to go out in search of fodder for the army's horses and pack animals. In medieval and early modern warfare, armies required enormous quantities of fodder — a cavalry horse consumed 20-30 pounds of hay per day. The foraging party, the fourrage, was a military necessity as much as a fighting operation.

The foray was the military operation by which the foraging was conducted: a party of soldiers rode out into enemy-controlled territory, gathered fodder and supplies, and returned before the enemy could concentrate to stop them. The foray required speed, local knowledge, and the ability to withdraw quickly under pressure. Edward III of England's raids into France during the Hundred Years' War — the chevauchées — were organized forays on a massive scale, designed to devastate the countryside and undermine the French king's ability to feed his population.

The word shifted from its specific military meaning toward any quick, purposeful incursion. By the 17th and 18th centuries, a foray could be a commercial expedition (merchants making a foray into a new market), a diplomatic venture, or a personal excursion into unfamiliar territory. The military flavor remained — a foray still implied going somewhere that was not entirely your own territory, something quick and purposeful rather than a settled presence.

Today foray names any first or tentative entry into a new area — a first foray into painting, a company's foray into a new market, a politician's foray into economic policy. The military element is mostly gone: what remains is the sense of a purposeful excursion into territory not yet occupied, with the understanding that you might withdraw if things go badly.