On July 4, 1187, the Crusader army, led by King Guy of Jerusalem, marched across the searing plains of Galilee to relieve besieged Tiberias. But Saladin was waiting. He cut off their water, surrounded them, and set the dry grass ablaze. As smoke and heat choked the air, the Knights Templar and Hospitallers formed a desperate circle around the True Cross, the holiest relic in Christendom.

Hour after hour, they fought — outnumbered, dehydrated, burning beneath the sun. Their horses fell first, th...  more