In which historical conflict is the first Assassin's Creed game primarily set?

The first Assassin's Creed game is primarily set during the Third Crusade.

Its historical sections take place in 1191, when Altaïr Ibn-La'Ahad carries out missions in cities including Jerusalem, Acre, and Damascus. The game places its fictional Assassin–Templar struggle alongside real events and figures from the crusading period.

The Third Crusade lasted from 1189 to 1192 and followed the capture of Jerusalem by Saladin in 1187. Major European leaders involved included Richard I of England, Philip II of France, and Frederick I Barbarossa, although the game adapts history for its fictional narrative.

The game does not present a documentary account of the Crusades. Its modern-day framing device and secret societies are fictional elements, while the locations, era, and several historical figures draw on the real medieval conflict.