campaign: [17] Ultimately, campaign and champagne are the same word. Both go back to late Latin campānia, a derivative of Latin campus ‘open field’ (source of English camp). This passed into Old French as champagne and into Italian as campagna ‘open country’, and both words have subsequently come to be used as the designation of regions in France and Italy (whence English champagne [17], wine made in the Champagne area of eastern France).
The French word was also borrowed into English much earlier, as the now archaic champaign ‘open country’ [14]. Meanwhile, in Italian a particular military application of campagna had arisen: armies disliked fighting in winter because of the bad weather, so they stayed in camp, not emerging to do battle in the open countryside (the campagna) until summer. Hence campagna came to mean ‘military operations’; it was borrowed in to French as campagne, and thence into English. => camp, champagne
1640s, "operation of an army in the field," during a single season, in a particular region, or in a definite enterprise; from French campagne "campaign," literally "open country," from Old French champagne "countryside, open country" (suited to military maneuvers), from Late Latin campania "level country" (source of Italian campagna, Spanish campaña, Portuguese campanha), from Latin campus "a field" (see campus). Old armies spent winters in quarters and took to the "open field" to seek battle in summer. Extension of meaning to "political activity before an election, marked by organized action in influencing the voters" [DAE] is American English, 1809.