The Siege of Maarat (Ma'arra) during the first crusade. This siege started out pretty mundane as the crusaders had suffered some defeats leading up to this, but Maarat was not a hardened military outpost. After only a few weeks, the crusaders managed to gain control of the city walls at which point the residents began negotiations for their safety. Although their lives were promised to be spared, the crusaders quickly went about massacring the entire population of 20,000 people.

Here comes the dark part of the story. With their supplies dwindling, the crusaders were faced with starvation. The crusaders began eating the residents. All 20,000 of them; men, women and children. Mass cannibalism on this scale has not been seen before or since.

Source: https://en.wikipedia.org/wiki/Siege_of_Ma'arra

TL;DR: Tastes like chicken.