You must have heard of the phrase “a Pyrrhic victory”; a victory that is obtained with so much loss that it might as well have been a defeat.
The phrase stems from the Pyrrhic War (280-275 BC), a war of shifting alliances between the Greeks, Romans, and Carthaginians. Pyrrhus of Epirus, a Greek state in the western Balkans, battled the Romans in 280 BC and 279 BC, at Heraclea and Asculum respectively. He suffered incredible losses, but won both battles simply by virtue of having lost less men than the Romans. However, because Rome had a much larger supply of men, the damage that was done to their war-effort was less than the damage to Pyrrhus’ supplies.
In a report, Plutarch attributes the following quote to Pyrrhus: “[O]ne more such victory would utterly undo [me]”.
Whether or not this is the bloodiest conflict we can’t be certain, but it has definitely become a representation of a win at such an incredibly high toll that it takes away any sense of achievement or profit.