Crusader Castles, Sieges and Frontiers: Defence in the Levant

From the establishment of the County of Edessa and the Principality of Antioch in the late eleventh century to the fall of Acre in 1291, fortifications helped Latin rulers hold territory in the Levant. They guarded roads, river crossings, ports and approaches to settlements, and served as military bases and administrative centres. Their effectiveness depended on provisioned garrisons and field forces that could relieve a threatened stronghold.

The Latin newcomers were often called Franks, whatever their place of origin. They governed territories with limited military resources and a diverse population. Their system of defence therefore combined castles and fortified towns with local agreements, troops supplied by landholders and the military orders, and reinforcements arriving from Europe. The balance between these elements changed over time, particularly after the Kingdom of Jerusalem’s defeat at Hattin in 1187.

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Fortifications and the work of holding a frontier

Castles served more than one purpose. A stronghold could protect a road or crossing, shelter a garrison, discourage raids and provide a base for operations nearby. It could also help rulers collect revenues and exercise authority over surrounding lands. Some fortifications were small towers or strongholds; others were parts of larger systems that included a fortified town, port or several linked castles. Many used or strengthened existing sites rather than beginning entirely anew.

Location shaped a fortress’s role. In the Kingdom of Jerusalem, strongholds near the Jordan valley and routes through the interior helped defend exposed approaches. In the north, fortifications served territories with different borders and strategic concerns, including the Principality of Antioch and the County of Tripoli. Coastal towns were especially valuable because they connected the Latin territories to maritime traffic and supplies from Europe.

Ascalon illustrates how a group of fortifications could contain a threat without relying on a single castle. The Fatimid-held port was a base for attacks on the Kingdom of Jerusalem. Between 1136 and 1149, the Franks built strongholds at Ibelin, Blanchegarde, Beth Gibelin and Gaza around it. The network helped constrain Ascalon and its raids. It did not make the port irrelevant: Ascalon remained in Fatimid hands until its capture in 1153.

Territorial defence also depended on who could hold the strongholds. The military orders, including the Hospitallers and Templars, became important garrisoning forces. Their European and Levantine estates provided revenue, and their network of branch houses helped transfer money and goods. A share of the income commonly went to their headquarters in the East. Lords also relied on vassals, hired soldiers and visitors from Europe. The resulting force was not a single, permanently unified army, and a castle’s defensive value depended on whether its garrison could be maintained.

Building, garrisoning and supplying castles

Builders generally used materials available nearby. In northern Jordan and around the Sea of Galilee, for example, basalt was available; limestone was used in other areas. A common wall construction had an outer and inner face, with rubble and mortar packed between them. Reusing stone from older buildings could save labour and materials. At Jacob’s Ford, the archaeological evidence includes unfinished masonry, building tools, mortar and traces of cart routes between the fortress and a nearby quarry. Construction there was interrupted before the castle was complete.

A castle’s defensive spaces had to support everyday work as well as fighting. Garrison members needed places to sleep, eat and store provisions and military equipment. Larger strongholds had kitchens, ovens, stables and store rooms, as well as religious and administrative spaces. In military-order castles, shared halls and routines reflected communal religious life.

Water was a particular concern, especially during a siege. Castles used wells, cisterns, rainwater collection or conduits where available. Belvoir Castle had two cisterns, with stated capacities of 100 and 650 cubic metres; water from its roofs was channelled to storage. At Krak des Chevaliers, the Hospitaller fortress had water facilities for ordinary use and a well 27 metres deep that could be used during a siege. Its vaulted spaces also included a long storage area, a bakery and toilets. Stored grain, ovens and water reserves allowed brothers and other defenders to remain inside while a siege interrupted outside deliveries.

Later fortresses developed more layered defences. In a concentric design, an inner line of walls and towers stood behind an outer one, forcing attackers to overcome successive barriers. Projecting towers allowed defenders to cover sections of wall, while narrow or angled entrances exposed people approaching the gate to fire from the sides. Small, discreet exits, often called posterns, let defenders make a sortie, meaning a brief attack outside the walls, without opening the main gate. These designs made access harder and gave a smaller garrison more ways to resist, but they demanded resources to build and maintain.

How a siege was fought

A besieging army could try to cut a town or fortress off from food, water and relief. A blockade might force surrender without a direct assault, but it took time and required the attackers to maintain their own supplies and positions. Alternatively, they could bring engines to bear on the walls or attempt to reach them with siege towers and battering rams. A siege tower was a large wooden structure used to bring attackers close to the defenders’ positions. Its upper platform brought men toward the parapet, sometimes using a bridge to cross onto the wall. Timber, carpenters and protection from defenders’ missiles were needed to build and move it.

Stone-throwing engines battered defences from outside missile range. A trebuchet swung a long wooden arm carrying a sling: men pulling ropes, or a falling counterweight in later designs, drove the arm around and released its stone toward the target. The crew reloaded and reset the machine for each shot.

Attackers could also dig beneath a wall, weakening its foundations until part of it collapsed. Defenders responded by repairing damage, attacking siege works and making sorties. Siege warfare therefore involved more than the moment of assault: both sides had to protect their workers and supply lines, watch for relief forces and preserve enough strength to continue. In the region, commanders also used signal fires and carrier pigeons to communicate news of military movements.

The early Crusader sieges show how different methods could produce different outcomes. Antioch, besieged from 1097, was taken in 1098 after a commander within the city helped the Franks enter. They then faced a relief army outside the walls. Jerusalem fell to the First Crusade on 15 July 1099 after a siege of a little over a month and an assault on the city. Tripoli, by contrast, endured a seven-year siege before its capture in 1109. These events show that a town’s fate depended not only on its walls but on access, internal circumstances, relief and the endurance of besiegers and defenders.

Jacob’s Ford shows how mining could defeat an unfinished stronghold. Construction began in 1178 at a crossing of the Jordan River. In August 1179, Saladin’s forces dug beneath the northern wall and opened a breach. The fortress had not been completed: archaeological remains include unfinished walls, scaffolding and construction materials. This evidence helps explain the vulnerability of a new castle under attack. The defenders faced not only a breach but an assault on a position whose planned protections were still incomplete.

Hattin and the changing role of castles

Before Hattin, the Latin rulers could expect a field army to confront an invading force and potentially relieve a besieged castle. That did not make castles unimportant, but it meant they were part of a wider defensive system. The defeat at Hattin on 4 July 1187 destroyed much of the Kingdom of Jerusalem’s army. Saladin then captured Jerusalem later that year, and much of the kingdom’s territory was lost. With fewer troops available to challenge armies in the field, strongholds became more central to defence.

The change was not simply a matter of building larger walls. Castles increasingly had to withstand attack for longer and operate with less expectation of immediate relief. At Belvoir, defenders used posterns to leave the fortress and attack besiegers during Saladin’s siege in 1188. Such sorties could disrupt a besieging force, but they could not reverse the wider military balance on their own. Siege engines could throw stones at walls and defenders, while the attackers’ capacity to maintain a siege depended on supply and control of the surrounding area.

These changes also shaped the selection of sites and defensive layouts. High or steep ground made it harder to bring attackers and engines close to the walls. Outer defences, towers and sloping wall bases could complicate both assault and mining. Krak des Chevaliers developed into a major Hospitaller stronghold with layered defences and extensive internal facilities. Its design shows how protection and the practical needs of a standing garrison could be brought together, though even a formidable fortress remained vulnerable if isolated or overwhelmed.

Mamluk campaigns and the fall of the coastal strongholds

In the later thirteenth century, Mamluk rulers based in Egypt and Syria captured Latin strongholds one by one. Their campaigns combined pressure on individual castles and cities with the use of siege engines and the destruction of fortifications after capture, which made it harder for enemies to reuse them. The loss of inland and northern strongholds left the remaining Latin territory increasingly concentrated on the coast.

Acre, the principal remaining centre of the Kingdom of Jerusalem, fell in 1291 after a siege by the Mamluks. Its double line of walls was not enough to compensate for an undermanned defence. The Mamluk army brought siege engines against the city. The fall of Acre ended the kingdom’s rule on the mainland. The history of the region’s fortifications thus reflects the contraction of the Latin territories: repeated conquests deprived neighbouring garrisons of ports, revenues and possible relief.