The Crusader forces besieging the high walls of Haifa were unprepared for the fierce resistance they met. On the ramparts, Jews and Muslims fought side by side, simple laborers and soldiers, united by the danger they faced

In 1071, the Byzantine Empire was dealt a crippling blow when a tribe of Mongolians conquered Anatolia, today a popular tourist destination in Turkey. The Seljuks, as they were called, had left the Russian steppes to conquer Central Asia, converting to Islam along the way. With North Africa as well as the Iberian Peninsula firmly in Muslim hands, and the Seljuks now gnawing at its eastern border, Christian Europe was virtually surrounded.

Byzantium, the eastern half of the Roman Empire, had been fading for a while. Its leader, former general Alexius I Comnenus, realized that without substantial allies, he couldn’t withstand the marauders for long. Ignoring the centuries-old feud that divided Byzantium from the western Holy Roman Empire, Alexius asked Pope Urban II to send in mercenaries as reinforcements. The pope agreed, hoping to unite all Christendom under his leadership.

In the winter of 1095, at the Church’s major council in Clermont, France, Urban ordered all clergy to urge the liberation of Jerusalem from the Muslim infidels. The pope’s call to violence, plunder, and adventure struck a chord (much as similar messages do among jihadists today), and soon every segment of the population was raring to go.

An ill-prepared rabble set out in the spring of 1096, little knowing even where Byzantium was, let alone the Holy Land. These Crusaders headed east through the Rhine Valley, seizing supplies and equipment mainly from defenseless Jewish communities, “the infidel in their midst,” and leaving a trail of murder, rape, pillage, and destruction. Twelve thousand Jews died in this first “People’s Crusade,” which continued along the Danube toward Jerusalem. But when Hungarian villages fought back, killing a few thousand Crusaders, the leaders fled homeward, and the rest dispersed with little to show for their trouble.

Later that summer, a “real army” of thirty-five thousand knights (including five thousand horsemen) set out, led by the flower of European nobility.