The lost crusade: in the 13th century, Christian crusaders who took up the cross to liberate the Holy Land from Islam were misdirected into serving very different ends.

On the morning of June 24, 1204 A.D., the walls of Constantinople were thronged with curious spectators. Over the blue waters of the Bosporus, their sails full-bellied in the early summer wind, a vast and colorful armada was passing before the city. At its head was a vermilion-colored galley appointed for the transport of dignitaries. Behind the vermilion ship came the rest of the fleet, 480 warships in all: superbly-constructed vessels from the shipworks of Venice, full of tens of thousands of well-armed men and provisioned with horses, foodstuffs, and vast stockpiles of weapons, including fearsome siege engines like mangonels and petraries.

The citizens of ...