The Sultan of Persia made Zenghi governor of Mosul in 1127. Zenghi, who was the first Atabek, was a commander and organizer of ability, and with a soldier's instinct struck where his enemy was vulnerable. He first occupied Aleppo, Hamah, and Homs. He then achieved the triumph of his life by the capture of Edessa. The next year he was murdered, and was succeeded by his still more celebrated son, Nour-ed-Din, who made Aleppo his capital, and devoted his life to completing the work his father had begun.
After a series of brilliant campaigns, by a mixture of vigour and address, Nour-ed-Din made himself master of Damascus, and, operating thence as a base, he conquered Egypt, and occupied Cairo in 1169. During the Egyptian war, a young emir, named Saladin, rose rapidly into prominence. He was the nephew of the general in command, at whose death the caliph made him vizier, because he thought him pliable. In this the caliph was mistaken, for Saladin was a man of iron will and consummate ability. William of Tyre even accused him of having murdered the last Fatimite caliph with his own hands in order to cause the succession to pass to Nour-ed-Din, and to seize on the substance of power himself, as Nour-ed-Din's representative.
Certainly he administered Egypt in his own interest, and not in his master's; so much so that Nour-ed-Din, having failed to obtain obedience to his commands, had prepared to march against him in person, when, on the eve of his departure, he died. Saladin then moved on Damascus, and having defeated the army of El Melek, the heir to the crown, at Hamah, he had himself declared Sultan of Egypt and Syria.
With a power so centralized the Franks would probably, under the best circumstances, have been unable to cope. The weakness of the Christians was radical, and arose from the exuberance of their imagination, which caused them to proceed by miracles, or more correctly, by magical formulas. An exalted imagination was the basis of the characters of both Louis VII. and Saint Bernard, and the faith resulting therefrom led to the defeat of the second crusade.
The Christian collapse began with the fall of Edessa, for the County of Edessa was the extreme northeastern state of the Latin community, and the key to the cities of the plain. When the first crusaders reached Armenia, Baldwin, brother of Godfrey de Bouillon, conceived the idea of carving a kingdom for himself out of the Christian country to the south of the Taurus range. Taking with him such pilgrims as he could persuade to go, he started from Mamistra, just north of the modern Alexandretta, and marched east along the caravan road. Edessa lay sixteen hours' ride beyond the Euphrates, and he reached it in safety.