A "Pyrrhic Victory" is a victory fought at a great cost to the victor.

Its origin stems from the war between the people of Epirus in ancient Greece, and the Romans between 280 and 275 BC. The king of Epirus was called Pyrrhus, and he was asked by one of his allies to help defend them against the Romans.

Pyhrrus agreed to this and was subsequently involved in the battle of Heraclea, against a powerful Roman Army.

Eventually, Pyrrhus won the battle, but most of his soldiers, including his friends and high ranking officers, were slaughtered. The Romans lost many more men, but they had plenty more in reserve.

When the battle was over Pyhrrus did not consider it a victory and was heard to state that if he was involved in another battle like Heraclea that he would be returning to Epirus on his own.

The Romans, with their superior numbers and weapons, won the war and Pyrrhus was beheaded.

The term "a pyrrhic victory" is still used today when you have got something that you have badly wanted, but it cost you dearly.

More Info: en.wikipedia.org