Were the crusader states doomed from the start? Were they inherently nonviable? Most commentators point to the Battles of Hattin and/or La Forbie as the "beginning of the end." Yet the Kingdom of Jerusalem was almost fully restored to its pre-Hattin borders in 1243, and in retrospect even La Forbie was only an apparent and not a substantive turning point. In fact, their doom was not inevitable.
The battle of La Forbie was not a clash between Christians and Muslims, but rather between Ayyubid princes, in which the Franks had the misfortune to back the losing side. Notably, the defeat did not result in the Kingdom of Jerusalem being over-run and destroyed — precisely because the victor was not engaged in jihad. Thus, decisive as this battle appears, it was not the cause of subsequent decline. As long as the Ayyubid princes remained in control of the territories surrounding the crusader states, it was possible to 1) make truces with them, and 2) play them off against one another. The Ayyubids were far too interested in profiting from the trade they had with the crusader states to undertake serious jihad. It was not until the rise of the Mamluks that the crusaders faced opponents set on their destruction and eradication.
The Mamluks were not a dynasty, but a cadre of fanatical, orthodox, military leaders willing to sacrifice economic considerations for religious orthodoxy and victory. The Mamluks pursued a ruthless policy of aggression against the crusader states that included routinely breaking truces, breaking the terms of truces, slaughtering prisoners, and engaging in the wanton destruction of economic assets and cultural monuments to render the cities they captured uninhabitable for generations to come. The Mamluks did not pursue wars of conquest in which they hoped to occupy and benefit from the territory they conquered but rather wars of annihilation.
Yet the Mamluks alone are not responsible for the destruction of the crusader states. The rot came from the inside. From 1100 to 1225, Jerusalem was ruled by kings resident in the kingdom, who viewed the defense of the Holy Land as their raison d’etre. From Baldwin I to John de Brienne, these kings had been fighting men devoted to the kingdom they inherited, whether by blood or marriage.
In 1225, that changed. The marriage of the heiress of Jerusalem, Yolanda, to the Holy Roman Emperor Frederick II Hohenstaufen, put the crown — and fate — of Jerusalem into the hands of a man who already possessed a vast Empire. As events were to prove, Frederick II never gave more than a tinker’s damn about Jerusalem or the Kingdom named after it. He spent less than a year in the kingdom, he ignored its constitution, sought to humiliate and break the local barons, and on his death bed in 1250 tried to alienate it from the legitimate heir. His son and grandson were titular “Kings of Jerusalem,” who never set foot in the kingdom, had no understanding of its laws, people or problems, and exercised no influence there. Their worthless rule was followed by a succession crisis that was not solved until 1284, when the kingdom was already beyond salvage.
In short, between 1225 and 1284, the Kingdom of Jerusalem effectively had no central authority. It is hardly surprising that in the circumstances internal factions formed, and that clashes over policy led to bloodshed. Without central authority, the barons soon resorted to pursuing independent policies that further eroded the state, while the Italian city-states pursued their commercial rivalries without the least regard for the impact on the viability of the Latin East.
None of this was inevitable. The crusader states, backed with the resources of Cyprus, might well have held their own against the Mamluks and Mongols, if they had been led by a strong, determined and militarily capable king. This was effectively what the barons of Jerusalem had sought in 1190, when they rejected the leadership of the ineffectual Guy de Lusignan and chose Conrad de Montferrat as the king-consort of their queen. In the thirteenth century, they would have needed to reject the ‘legitimate’ Hohenstaufen kings in favor a truly elected king committed to the defence of the Holy Land — say Simon de Montfort. However, the barons of Outremer, despite their ‘rebellion,’ were ultimately too conservative to take the leap necessary for the sake of their existence. Yet that assessment, obviously, is the wisdom of hindsight.
The bulk of this entry is an excerpt from Dr. Schrader's comprehensive study of the crusader states.