When I was growing up as a Nice Jewish Boy in day school, we were taught that the Crusades were one of the worst episodes in history: marauding Christian soldiers massacring everyone in sight. Especially Jews.

Most historians tend to agree that the Crusades were a dark chapter in Christian history, with extraordinary violence carried out in Christ’s name, and with Christian doctrine often a mere excuse for murder and pillage. This, no doubt, is why President Obama mentioned the Crusades as an example of heinous religious violence last week.

It would seem to be an uncontroversial claim. Historians estimate that between one and three million people died in the Crusades (including the Crusaders), at a time when the world’s population was 300 million. That’s right—up to 1 percent of the entire world population perished in the paroxysms of violence between 1095 and 1291. The equivalent of sixty million people today.