Castle Defenses in Medieval Europe

Layers of Strong Walls Ensured the Ability to Withstand Sieges

Jun 2, 2009

The evolution of castle defense began in the 9th Century and saw dramatic improvement coming out of the Crusader movement, creating impregnable fortifications.

The medieval castle can be traced back to the Roman fortifications built in response to barbarians crossing into frontier areas. During the post-Roman period, early motte-and-bailey constructions gave way to larger and stronger castles or burgs, particularly during the Viking and Magyar incursions in the 8th and 9th Centuries. The period of the Crusades, however, brought innovation and the development of several defensive additions.

The Earliest European Castles

Post-Roman era “castles” were generally simple structures that served immediate military and administrative purposes. Usually built of wood and either on higher ground or near a river, these castles represented a refuge for townspeople living outside the walls and contained the lord’s home, often a keep.

An anecdote from the 9th Century relates a Viking raid along the coast of France at a small seaside town. Charlemagne was visiting the area and heard the tumult from the castle, built on a hill overlooking the village. Although gathering a small force to stop the Vikings, Charlemagne was unable to react swiftly enough and the Vikings managed to return to the sea.

Even before the era of Crusading began in the late 11th Century, stone was replacing wooden walls. Constantinople was considered the most impregnable city with three separate walls protecting the Byzantine capital; the other sides of the city were protected by the waters connecting the Black Sea with the Bosporus and the Dardanelles.

At Constantinople, a low outer wall represented the first line of defense, followed by a moat. The second wall, some six feet tall, was connected by towers. Finally, the third or inner wall, also connected by towers, was thirty feet tall and so massive that catapult could be positioned. This wall also contained openings for the use of crossbows.

Multiple walls often saved a castle during a long siege. In 1204, the outer wall or “barbican” at Carcassonne, though breached in several areas due to mining or “tunneling,” stopped invaders from reaching the primary walls (see image below).

Mining referred to the digging of a tunnel under either the outer walls or beneath a tower connected to the interior wall. Flammable material filled the tunnel – including dead pigs (to fuel the blaze). If successful, the wooden tunnel frames would give way, bringing down the wall or tower and creating an opening to be exploited by the invader.

Good Defenses Provided Distinct Advantages

Castles could be defended by smaller numbers of men if well constructed and if enough supplies had been stored for a long siege. This included a reliable water source. Joseph and Frances Gies, medieval historians, postulate that “a garrison of sixty men could hold out against an attacking force ten times its number…” (188).

Assuming an enemy breached the outer walls and the moat, the castle was protected by heavy doors, usually covered by the drawbridge and reinforced by a portcullis or grated gate, lowered to protect the doorway. If an enemy managed entry, they would pass, initially, through a passageway featuring “murder holes,” used to ambush intruders.

Finally, the battlement crenulation offered protection to soldiers on the walls, using crossbows and other weapons to stop an attack. Castle defenses were generally so good that the only options involved starving out the defenders or disrupting the water supply.

Decline of Castles

The Hundred Years’ War, begun in 1337, led to the end of castle building with the introduction of gun power and the early use of crude cannons during the final phase of the conflict. In many cases, towns surrounding well fortified castles had grown tremendously while, as in the case of the Welsh castles, the region had been pacified, ending the effective use of castles.

The copyright of the article Castle Defenses in Medieval Europe in Medieval History is owned by Michael Streich. Permission to republish Castle Defenses in Medieval Europe in print or online must be granted by the author in writing.