A victory that is so costly in terms of men and resources that it seems no different from losing. It comes from King Pyrrhus of Epirus, who was fighting against the Romans in the Pyrrhic Wars (c.280BCE). Pyrrhus is supposed to have said 'If we are victorious in one more battle with the Romans, we shall be utterly ruined' (Plutarch, Life of Pyrrhus, 21:8).
Fact of the Day
Elizabeth I could cost her hosts so much on her visits that some tried to shut up their houses and stay away to prevent it. This did no good for the earl of Lincoln: Elizabeth broke into his Chelsea residence, had a feast, and then charged the bill to Lincoln.