Campaigns are remembered for battles, but they are usually decided by supply. An army eats, burns fuel, and expends ammunition at a rate that does not pause between engagements, and every mile it advances lengthens the line along which those things must travel. A force that outruns its supply becomes weaker the further it goes, while a defender falling back toward its own depots grows stronger. This is why an advance that looks unstoppable on a map can stall without a shot being fired against it, and why planners spend far more time on tonnage and road capacity than the histories usually record.