The Hammer of God — Robert M. Johnson

The newly established Kingdom of Jerusalem, the Holy City, maintained a shaky equilibrium in its first years of existence starting in 1099 A.D.
The Great Crusade was over, now came the really hard part: solidifying and stabilizing the gains made by four years of pilgrim warfare. Christendom had taken back the Holy Land for the first time in over 500 years, and Jerusalem was the crown jewel.
Pilgrims began immediately flocking to the land of Jesus Christ by the thousands. Some came overland, but most arrive by Sea and flowed through the seaport cities of Ascalon, Jaffa and Caesaria. Their short journey to the Holy City from the seashore meant running a gauntlet of brigands and marauding Saracen mercenaries.
Matthew of Cologne had opted to stay in the Holy Land after the Crusade. He had become an important battle commander for the new King of Jerusalem, Baldwin I, who was the brother of Matthew's Mentor, Godfrey of Bouillon.
Matthew became close friends with another ex-crusader, Hugh de Payans. Together they would form a religious order that would change the course of Christian History: The Knights Templar.