" it soon proved Pyrrhic."
Bust of Pyrrhus of Epirus
Public DomainBust of Pyrrhus of Epirus - Credit: Wikimedia Commons

The expression Pyrrhic Victory refers to a victory which is won at too high a cost and is most probably the last sustainable victory possible.  It refers to King Pyrrhus of Epirus who led his armies against the Romans at Heraclea in 280BC and at Asculum in 279BC during the Pyrrhic War.  Although he inflicted heavy losses on the Romans, he lost many of his men, including his best warriors.  And ultimately, the Romans had far greater numbers on which to draw for future conflicts than did Pyrrhus.  So, in victory Pyrrhus was the ultimate loser.