What were the Crusades actually about?

Urban II preached at Clermont in November 1095. Five accounts of what he said survive, by Fulcher of Chartres, Robert the Monk, the anonymous author of the Gesta Francorum, Balderic of Dol and Guibert of Nogent, along with a letter Urban wrote that December.

They were written afterwards: the Gesta around 1100, Balderic in the early twelfth century, and Robert, on the dating of his editors Kempf and Bull, shortly after 1108. All of them after the crusade had succeeded and had to be explained.

They do not agree. Fulcher has him redirecting private warfare: "let those who have been accustomed unjustly to wage private warfare against the faithful now go against the infidels." Guibert has providence: "consider, therefore, that the Almighty has provided you, perhaps, for this purpose, that through you He may restore Jerusalem."

Before any army reached the eastern Mediterranean, crusading bands passing through the Rhineland attacked Jewish communities. Albert of Aix, a Christian chronicler with no reason to invent it, writes that they "rose in a spirit of cruelty against the Jewish people scattered throughout these cities and slaughtered them without mercy".

The same account has Rothard, the archbishop of Mainz, take the Jews and their money into "the very spacious hall of his own house ... that they might remain safe and sound", and then has Emico’s band attack them there anyway. Albert counts about seven hundred dead in that one place, and then adds the women and children. Solomon bar Samson’s Hebrew account, written around 1140, gives eleven hundred.

Both accounts have a bishop offering shelter and men who believed themselves on a holy errand killing. The Hebrew one adds that the bishop’s men were the first to flee, and the bishop after them. Albert himself judged that the killers acted "through greed of money, rather than for the sake of God’s justice". Any account that keeps only the sheltering or only the killing is quoting selectively.

The main army of the fourth crusade never reached the Holy Land. It took Constantinople, the imperial city of the Christian East, in April 1204, and Innocent III, who had called the crusade, condemned it more than a year later in a letter to his own legate: they "have spared neither age nor sex", they "ripped silver plates from the altars and have hacked them to pieces", their swords "are now dripping with Christian blood".

This is not a later verdict by an opponent. It is the pope who had called the crusade, in office, in a letter that survives. He also accepted what it had won: he recognised the Latin empire the crusaders set up, and made bringing the Greek church under Rome his aim.

One explanation is as old as the expedition: a contemporary put the part the masses took in it down to disorder, disease and economic distress. Jonathan Riley-Smith, reading the narratives and charters, which is how some 880 participants in the first crusade have been identified at all, finds very little evidence of anyone coming home rich. Going cost money: in Fulcher’s version Urban tells those who go to rent out their lands to pay for it.

A man can be sincere and be part of a massacre, which is most of what makes this material hard.

The crusader states in the Levant lasted nearly two centuries, held by Franks who stayed distinct from the peoples they now lived among. Whether to call that colonial has been argued over the ground itself. Joshua Prawer held that the Franks settled in the cities and kept out of the countryside for security; Ronnie Ellenblum sets the debate out as two approaches, one stressing what the settlers brought from Europe and the other what they took from the Levant.

The disagreement is genuine and it matters, because the word carries a modern argument into a medieval one in both directions.

The chroniclers count in the way medieval chroniclers count, which is to say rhetorically. For Jerusalem in 1099, Fulcher of Chartres puts almost ten thousand dead in one temple, and the Gesta says that no one knows their number except God. The Arabic reports that make the massacre largest belong to a tradition that formed later and elsewhere: Ibn al-Athir’s famous report, written over a century after the event, goes back almost entirely to a Baghdad strand that the early Egyptian and Syrian accounts do not share.

That is a caution about scale, not about whether there was a massacre. The Latin chroniclers describe one, and one of them calls it "a just and splendid judgment of God". What Konrad Hirschler argues the early Egyptian and Syrian evidence makes highly unlikely is the killing of the entire population.

It cannot be recovered. What survives is five reconstructions by men who knew how the story ended and were explaining it as God’s work, plus one letter issued in his name that is much drier than any of them.

The speech that began the crusades is a speech nobody wrote down at the time.

In March 2000 John Paul II asked pardon publicly "for the divisions which have occurred among Christians, for the violence some have used in the service of the truth and for the distrustful and hostile attitudes sometimes taken towards the followers of other religions", acknowledging "the infidelities to the Gospel committed by some of our brethren, especially during the second millennium".

It names violence in the service of truth rather than any single episode. A year later, in Athens, he named one: "the disastrous sack of the imperial city of Constantinople", whose assailants "turned against their own brothers in the faith", and he asked forgiveness for the times Catholics had sinned against the Orthodox. Whether words like these are the right way to answer for specific dead people is a fair question.

The Crusades are used as a summary of Christianity by people who want one, in both directions: proof that the religion is violent, or proof that it defended itself. Both uses need the evidence to be simpler than it is.

What the sources support is narrower and stranger: a speech nobody has, a massacre before the war started, a holy expedition that sacked Constantinople, and a pope who condemned it in writing and kept what it had won.