Who called the christian worriors to fight against the Muslims?

The Christian warriors were primarily called to fight against Muslims during the Crusades, which began in the late 11th century. Pope Urban II is notably recognized for initiating the First Crusade in 1095, urging Christians to reclaim the Holy Land from Muslim control. His call was framed as a religious duty, promising spiritual rewards for those who participated. This mobilization led to a series of military campaigns over the following centuries.