At Easter in 1147, 130 Templar knights assembled in Paris, drawn there as part of a huge army gathered to join the Second Crusade to liberate the city of Edessa in the Holy Land. The knights would have been a striking sight, wearing white mantles with a red cross emblazoned across their uniforms.

Leading the French crusaders was King Louis VII, whose personal piety was such a hallmark of his kingship that his wife, the fiercely intelligent southern duchess Eleanor of Aquitaine, sometimes wondered if she had married a monk and not a king. Tears were shed and prayers recited by the crowd who had come to see the king leave. Not for 50 years had there been such crusading fervor in the West.

Little by little, as Louis’s forces made their way east, it became clear that his army was in fact little more than a pious but incompetent rabble. Were it not for the Knights of the Temple, it is likely they would never have made it within sight of the Holy Land at all.

The French arrived in Constantinople in the autumn, then set out through Asia Minor toward northern Syria. The road took them through wild and inhospitable country, littered with the corpses of German crusaders who had fallen there the previous year and lay still unburied. On January 8, 1148 they entered the difficult upland terrain of Mount Cadmus. Chronicler and eyewitness Odo of Deuil wrote of it as “an accursed mountain, steep and rocky,” which demanded that the long train of animals, wagons, foot soldiers and horsemen traverse “a ridge so lofty that its summit seemed to touch heaven and the stream in the hollow valley below to descend into hell.”

Worse, they had spotted Turkish outriders ahead.

Trying to guide a vast rabble over a mountain range proved quite beyond Louis VII’s capabilities. Disastrously, he allowed his army to separate and cross the peak of Mount Cadmus in three staggered groups. It was the opening the Turks shadowing the French had been waiting for. They fell on the baggage train and butchered its unarmed minders.

Odo of Deuil later recorded the panic he felt as the Turks “thrust and slashed, and the defenseless crowd fled or fell like sheep.” Louis himself was nearly killed; he only escaped a rush by Turkish attackers by scrambling up a rock covered in tree roots and battering back his assailants with his sword until they tired of the pursuit and rode away.

The Templars, far better trained for the reality of combat in the East than their comrades, came through the debacle on Mount Cadmus in remarkably good shape. Although most of the king’s troops were prone to disobedience and panic, the Templars had spent the march helping those around them survive the Turkish assault.

Perhaps most important, the Templar contingent was led by the French master Everard of Barres, whom Louis trusted. Now Everard’s influence with the king and the manifest superiority of his men to the rest of the army transformed the entire expedition, as Louis did something quite astonishing: He signed over effective command of the entire mission to the Templar knights. That allowed them to reorganize the military structure, take control of training and tactics and—most extraordinary of all—to temporarily enlist into the order every person in the vast royal following, from the meanest pilgrim to the mightiest knight.

Suddenly the Templars were no longer a small but competent unit within the larger French army of the Second Crusade. They were its leaders, and every man who followed them was, for a few weeks at least, a brother.

A Templar by the name of Gilbert was given overall field command. The ordinary French knights were formed into divisions of 50, each one commanded by a single Templar who reported to Gilbert. Soon the new command began drilling the troops in the art of fighting the Turks.

“Our men were commanded to endure the attacks of the enemies, until they received an order; and to withdraw immediately when recalled... When they had learned this, they were also taught the order of the march, so that a person in front would not rush to the rear and the guards on the flanks would not fall into disorder… Those whom nature or fortune had made foot soldiers...were drawn up at the very rear in order to oppose the enemies’ arrows with their bows.”

This was no great tactical innovation. Indeed, the fact that basic troop positioning and adherence to officers’ orders had to be taught to Louis’s followers illustrates just how woefully unprepared the crusaders had been to begin with.

All the same, with a little structure and the firm direction of their new Templar commanders, the crusader army descended from the mountains and rejoiced at reaching lower ground.

From this point on, the Templars were prominent agents in the political and military history of the Christian crusader states. They developed a network of castles, a set of military protocols and the institutional expertise necessary to carry out their task.

They also encountered some of the most extraordinary characters in the whole history of crusading, including the miserably afflicted leper-king of Jerusalem, Baldwin IV, the most famous Muslim sultan who ever lived, Saladin, and Richard the Lionheart, whose trust in and reliance on the Templars’ leading officials suggested the direction the order would take during the 13th century.

Even in defeat, the Templars loomed large as idealized crusaders. When Templar James of Maillé perished at the hands of Saracens in the battle of Cresson in 1187, his death was transformed into a Christian folk tale, and his corpse became a source of holy relics. Some admirers placed dust on the body and then sprinkled it on their own heads, hoping that it would infect them with the dead man’s valour. One man cut off his genitals “and kept them safely for begetting children so that even when dead, the man’s members—if such a thing were possible—would produce an heir with courage as great as his.”

Protected by royal patronage and papal favor, the Templars would begin to grow their landholdings, expand their property portfolio and enjoy lucrative tax breaks, making them dazzlingly wealthy and financially sophisticated…