In what year did the First Crusade begin?

The story behind the answer

Although Pope Urban II issued the call to crusade at the Council of Clermont in 1095, the actual expeditions formed and set out the next year. In spring 1096 the ill-fated People’s Crusade marched first, followed in late summer and autumn by the better-organized princes’ armies moving through Byzantium into Anatolia.

The movement responded to Byzantine appeals after Seljuk advances and aimed to secure access to holy sites; its success reshaped the eastern Mediterranean. The crusaders would not seize Jerusalem until 1099, after major battles like Dorylaeum (1097) and Antioch (1098), and the Latin states emerged soon after. This timeline explains why the start date is the year after Clermont’s call.