A Pyrrhic victory is battle won at too great a cost.
It is one in which the side that won the victory suffers very badly. A Pyrrhic victory may take place when the victorious army has lost a huge number of men or when the enemy army has reinforcements about to arrive which greatly outnumber the winning army and mean that the chances of a second victory are very low. A Pyrrhic victory is named after King Pyrrhus of Epirus. He won a battle against the Romans in 280 BC but many of his men and most of his friends and top commanders died in the battle.