A battle for God, church, and booty

They were savage and barbaric, with a special fondness for beheadings. Their spiritual leader assured them they were doing God's work and that if they died in battle, they'd go straight to heaven.

These weren't modern-day terrorists, but 11th-century Christian crusaders. At the behest of Pope Urban II, eager to shore up his position as the head of the church, they set out in 1095 to retake the holy city of Jerusalem. Urban's fictitious tales of Muslim atrocities - pure propaganda - had sent an electric shock through Europe. Some 100,000 people - knights, clergy, and peasants - began an armed pilgrimage, the biggest mobilization of manpower since the fall of the Roman Empire. It was a response that astounded Urban himself.

The four-year campaign fulfilled secular and spiritual ambitions, according to Thomas Asbridge, the author of this rousing history titled "The First Crusade." As both savage brutes and devout Christians, they attempted "a new form of 'super' penance: a venture so arduous, so utterly terrifying, as to be capable of canceling out any sin," he writes. Their violence was done in the name of God, using a radical interpretation of St. Augustine's "Just War" theory. (One apologist pointed out that Jesus had asked Peter only to put away his sword, not discard it, at the Garden of Gethsemane, obviously meaning that he would be called on to wield it in the future.)

Asbridge knows this territory well. In 1999, he even walked 350 miles of the crusaders' route. But he warns us not to read contemporary views of morality into this era. "In the minds of the crusaders, religious fervor, barbaric warfare, and a self-serving desire for material gain were not mutually exclusive experiences," he says, "but could all exist, entwined, in the same time and space." After the fall of Jerusalem on July 15, 1099, the knights went directly to worship at the Church of the Holy Sepulcher - the accepted site of the Crucifixion - bathed in their enemies' blood and carrying their booty with them.

Eventually, their reputation for "absolute ruthlessness" - at one point, nearing starvation, they resorted to cannibalism - helped them: Entire Muslim cities surrendered rather than face brutal annihilation.

Despite being drawn from many countries and speaking many languages, the crusaders slowly became a cohesive army under a council of princes. On the whole, the system worked well, though the leaders perpetually squabbled over power and wealth. (It also helped that they faced a series of fractious Muslim rulers.)

The pivotal battle, a prolonged siege of the great city of Antioch, tested the crusaders to the breaking point. A traitor finally let a band of them climb over a wall, and Antioch quickly fell, but just as a Muslim army was arriving to relieve the city. The besiegers suddenly became the besieged.

At this point, historians usually give great importance to the crusaders "finding" a powerful relic, the Holy Lance of Antioch, alleged to be a Roman spear with Jesus' blood on it. This gave them courage - some accounts say actual miraculous help - to rush out of the city and defeat a vastly superior force. More likely, Asbridge says, the crusaders simply recognized their hopeless position and, after failing to negotiate a withdrawal, decided that a bold attack was their only chance of survival.

Although all the conquered land eventually fell back into Muslim hands, the First Crusade was a seminal event, Asbridge says. It "set these two world religions on a course toward deep-seated animosity and enduring enmity," he notes, the "chilling reverberations" of which "still echo in the world today."

• Gregory M. Lamb is on the Monitor staff.