During the Islamic middle ages, besiegement was considered as one of the most frequent forms of military action. In order to ruin the resistance of the castle and take down the strong fenced cities, the raiders used various tricks, techniques, tools, and devices. Using ballistic devices, especially catapults, was extremely effective and determinative at the time. This article provides a documental description of various attack and defense functions of heavy ballistic armaments in castle wars of the Islamic period and examines how the utilisation of these kinds of weapons as a common technique in castle wars, is affecting the outcome of military operations during this historical period. It also showed that the aim of applying these armaments, the physical and destructive operational power, was not the only thing relied on, but it was partly for their ability to spread fear and panic and as a result, pushing a kind of psychological warfare against the enemy.