The Order's fortresses in Syria operated as commandries, but reported directly to the Grand Master. They were lead, especially in times of war, by a castellan who was a knight of the order, sometimes assisted by a commander. They were divided into three classes: two classes of lay brothers - knight brothers and sergeant brothers - and one class of cleric brothers, that is, chaplain brothers. They lived by the same monastic rule, inspired by Saint Augustin, and observed the three vows of obedience, poverty and chastity. The knight brothers and sergeant brothers were responsible for military affairs, while chaplain brothers celebrated religious services and served the pastoral needs of the lay community.
The originality of the fortresses built by the military orders lay in the combination of defensive, residential, and religious activities, with the dormitory, refectory and chapel in a single place.