The forces used by the Christian or Latin leaders in Syria were formed from a conglomeration of sources. Both the feudal system and changing conditions throughout the crusades made this necessary. The knights as discussed in the topic page on chivalry composed one portion of the army. It is important, however, to realize that while their influence remained important in the military tactics of the crusader states, their numbers dwindled towards the end of the crusades as the idea of the knight became increasingly associated with nobility and heredity of the title. When the influence of the knights was the weakest, other sources were found to supplement the knight in the army.
Besides feudal vassals, recruits for the army were taken from three other sources. In emergencies there was a standing obligation for all free men to serve when required. Mercenaries were increasingly hired to supplement the army, and the religious Orders of the Knights Templar and Hospitallars became increasingly important in the war effort. In addition, people who could not be counted in the main standing army, but who often helped in specific battles, were the religious pilgrims who were traveling to the Holy places.
This composition of forces made the Crusader's armies weak in a number of ways. "In the first generation of Frankish conquest their princes achieved success in war mainly by use of their feudal resources. The Orders of the Hospital and Temple were not yet militarized, and less was heard of mercenaries than in later years. Knightly vassals were available in numbers sufficient to protect and to extend Latin territories; they were generally loyal and obedient; their service was not subject to the limitations common in the West, but they were required to serve for the whole year if need be. During the course of the century the military problems of the Syrian Franks became more difficult. Earlier successes had been made possible by the divisions and political weakness of Islam. As Muslim Syria was first reunited and then joined with Egypt, the Franks needed increased military strength even to maintain the conquests of their predecessors; but the feudal servitium debitum certainly never expanded enough, and may even have contracted. The rulers were therefore obliged to rely more upon mercenaries, whose cost imposed an intolerable strain on their always insufficient financial resources, and upon the military Orders, whom they could not fully control"(Smail, 98).
The Crusader's main offensive military weapon was the mounted knight. As a large force, the charge of this heavy cavalry was a serious threat in any confrontation. The shock tactics that were used was dependent on the heavily armed knight with lance and sword on horse-back bearing down on an opponent at full speed. such a charge could inflict heavy damage on an enemy, however it requires great control over ones army to keep them under control in the face of mounted archers who would ride in and out of distance leaving arrows and dead horses in their wake. The Crusader's military tactics have been said to come from both common sense and a knowledge of Byzantine and Roman military tactics. Wherever their ideas came from, "it is clear, that to the Franks, an indispensable preliminary to any engagement was to subdivide the army into a number of smaller units and to marshal them in the field in a prearranged order"(Smail, 124). This tactic of starting in a regimented order was necessary as a battle began, to help facilitate the control that a commander would have over the army for as long as possible after the battle had begun. Turkish tactics of using archery against the Crusaders before the actual battle began, in order to unsettle the army, was difficult for European commanders to overcome. When the Islamic tactics worked, the main offensive threat of the Latin states, the charge of the Heavy Cavalry, was effectively removed. (Hurley, 39-41)
Final mention should be made of a problem that the European forces encountered in the Holy Lands. The problem of numerical weakness leading to the hiring of mercenaries has already been mentioned. Leading from this recruitment problem is one of tactics. There was a dual nature in the holdings of the Latin armies in Syria. The crusaders found themselves numerically inferior to the Islamic forces; especially toward the end of the Crusades. The armies were forced to both defeat field armies that the Muslims would have ravaging the countryside, as well as defend the strong places and castles. Often the numerical inferiority that the Crusaders would face allowed them to only choose one or the other. Defeating an Islamic field army meant that there would be no garrison left in a castle. The Crusaders could effectively loose their stronghold in an area when they were forced to face a field army or watch their livelihood be ruined and maintain a starving castle. (Smail, 106,117-119)