Battle of Aegates Islands (241 B.C.) - The battle which ended the First Punic War.  After 23 years of conflict in which both sides were thoroughly worn down, Rome finally outlasted Carthage and claimed victory.  It was a war fought mostly on water, and one of the conditions of Carthage's surrender was that it had to dismantle its navy.  This made Rome the dominant power at sea and forced Carthage to find another way to expand its empire.  However, Rome was so beat up as well, that it could not completely destroy Carthage, setting the stage for a second war only a generation later.