Latin armies drew on four main sources of soldiers, all of which had serious limitations. At the beginning, all Latin soldiers were essentially armed pilgrims from Europe. Each major crusade directed a substantial army at the Holy Land. Between crusades, a small but steady flow of pilgrims to the holy sites visited the Crusader States. Many were knights along with their retainers. They were available for a campaigning season, as pilgrim ships arrived in the Holy Land in April and left in October, but they were available only sporadically and temporarily. In contrast, once the Crusader States were established, their defense needs were permanent and on-going. Further, not all pilgrims were military personnel, and those who were, not being subjects of the local rulers, were only voluntarily obedient to their command.
Crusaders and pilgrims who did settle in the Holy Land became the backbone of the States’ systems of defense as well as the core of their ruling class. The settlers imported the socio-military structure of their homelands to their new possessions. Thus, the ruler of each state granted lands to his followers to administer and draw income from, in return for which they owed military service roughly proportional to the land’s value. Some grants were not of land, which was somewhat scarce, but of an annual fee in money derived from the active urban and maritime economy. The great nobles, in turn, granted parts of their estates to their followers to be used to maintain soldiers in their service. There were no limits on the service the ruler could demand, and the several Crusader States tended to support each other with their forces, but, as a system of property holding and administration, granting estates did limit the judicial powers of the ruler. Two problems plagued settler military forces. First, the districts most in need of defense forces were also those most liable to have their productivity damaged by Muslim raids. Maintaining forces at the frontiers without bankrupting the landholders was therefore a constant problem. Second, there were never enough landed settlers to provide an adequate defense.
The Latin rulers met some of the need for more troops by hiring mercenaries both from unlanded settlers and from Europe. Locals, especially the Turcopoles, who were the offspring of mixed unions, were often recruited in this way. But hiring a significant number of paid soldiers for any length of time always threatened the limited treasuries of the Latin states with bankruptcy, so while mercenaries were important on major campaigns, they could not be used to garrison castles on a permanent basis.
The problems of a standing defense force, especially in frontier regions, was alleviated in part by the rise of the Military Orders of the Knights of the Temple and of the Hospital. The Templars and the Hospitallers were, in effect, soldier-monks—knights who took vows of chastity, poverty, and obedience. The Orders developed sophisticated administrative structures with locations throughout Europe that directed recruits and funds to the Holy Land. Donating lands and money to the Orders was popular in Europe as an indirect contribution to the cause of crusading, and it became popular in the Holy Land as well because the Orders could garrison exposed frontier castles. They were not dependent on the local estates of a castle for income, and their knights were full-time soldiers. Their standards of discipline and training made them an elite among Latin forces, and they earned the special enmity of their Muslim foes. But the numbers of the Orders’ knights, while significant in the context of Latin armies as a whole, were never huge. More problematically, the Orders, as direct dependents of the pope, obeyed no secular ruler. They cooperated with the Latin rulers, especially in the Kingdom of Jerusalem where their lands were most numerous, but as independent allies, which complicated, and at times compromised, the Latin chain of command.
The sorts of soldiers, in terms of infantry and cavalry, raised from these four sources of manpower reflected the mix that had become typical in Europe in the eleventh century. The spearhead of Latin armies was the heavy cavalry of knights and sergeants, the latter (including the Turcopoles) armed like the knights but lower in social and legal rank. The cavalry wore chain-mail hauberks, often covered by a cloth surcoat, and iron helmets that became more complete and elaborate as the twelfth century progressed. They carried kite-shaped shields and fought with lance and sword. Horsemen formed a minority of the numbers in Latin armies—perhaps a fifth to a quarter at most. They were expensive to equip and maintain, and, at times, it was difficult to maintain an adequate supply of horses. But cavalry was the elite of armies both socially, as the legal status and privileges of knighthood became more defined in the twelfth century (though not all cavalry were knights or even landholders), and militarily, due to their greater economic resources, which gave them superior equipment and leisure for training in arms. The knights of the orders added religious prestige to their status as elite warriors.
The infantry consisted of landless adventurers, professional mercenary companies, the attendants of mounted men, and foot sergeants (men granted land for their service like knights and cavalry sergeants, but expected to serve only on foot)—in other words, a broad range of social types. On campaign, cavalry whose horses became unserviceable or died (not an unusual circumstance) became part of the infantry as well. Crossbowmen predominated, though spearmen were also common, and cavalry who fought on foot used their lances as infantry spears. Much of infantry must have been more transient from campaign to campaign than the cavalry of the landholders and Military Orders (yearly pilgrims were probably more likely to fight on foot, for instance). But regular campaigning would have produced an experienced core of foot soldiers in the Crusader States, and the infantry in crusader armies generally showed decent discipline and cohesion. Though less prestigious than the cavalry, the infantry were invaluable in defending and besieging fortifications and in providing a strong defensive base for the cavalry on the battlefield.