“Great efforts were made by builders to ensure that their castles could withstand an enemy onslaught.”

By Dr. Dan Spencer

IN THEIR DAY, Medieval castles represented the state-of-art in military engineering.

Erected by kings and feudal lords during what we now commonly call the Middle Ages, these foreboding strongholds dominated the territories upon which they stood, quartering garrisons of mounted soldiers used to control surrounding areas.

But more importantly, castles were defensive in nature, being skillfully designed to resist attacks by armies many times larger than those manning its parapets.

But of course, a castle was only ever as strong as its weakest point. As such, great efforts were made by builders to ensure that their castles could withstand an enemy onslaught. Here are 14 common features of castles that were designed to make life most unpleasant for attackers.

Natural Features

The strength of a castle was dependent upon many factors — one of the most important ones was its location. Placing a fortress in a naturally strong defensive position meant that it was that much harder for attackers to capture it. It’s for this reason that many castles are situated on the top of hills or cliffs. Dover Castle’s location on a coastal headland meant that it was tricky to besiege, as a Franco-baronial army found to their cost in 1216.

Reused Fortifications

Castle builders often made use of older existing Iron Age, Roman or Anglo-Saxon fortifications — very sensible considering that some of these fortresses were (and still are) impressive. At Old Sarum in Wiltshire, a castle, cathedral and city were built within the perimeter of an Iron Age hillfort following the Norman Conquest of England. The Normans also made use of some of the Saxon shore forts constructed by the Romans to provide coastal defence in the third century, such as at Pevensey in East Sussex and Portchester in Hampshire.

Walls

One of the most important features in a castle was its walls. Whether made of wood, stone or brick, they provided a barrier to enemy attackers. They typically included wall walks, which were used by the defenders to resist attempts to scale the walls or to shoot missiles at the besiegers. The battlements of a castle, such as at Pembroke Castle in Pembrokeshire, with their distinctive teeth-like appearance, also provided cover from enemy missiles.

Towers

Towers are another defining feature of what constitutes a castle. These could include mural towers that were situated along the length of the walls, or in some cases were the main structure in the fortress. Large towers (now known as keeps) were the central features of many of the greatest castles of the 12th century, such as at Rochester Castle in Kent.

Mottes

In some cases, the central towers of castles were situated on top of artificially created mounds known as mottes, which were linked to an adjoining bailey (an outer enclosure), as can be seen with Launceston Castle in Cornwall. This style of motte and bailey castle was particularly popular in the late 11^th to 12th centuries. Placing them on artificial hills meant that they physically dominated the surrounding landscape and were harder to storm during sieges.

Gatehouses

Gatehouses were often the most vulnerable part of a castle and therefore special efforts were made to defend them, this included murder-holes for dropping heavy objects onto the heads of attackers, metal bars or portcullises that could be lowered in front of wooden gates or drawbridges that could be raised against enemy armies. This can be seen with the fine gatehouse of Kidwelly Castle in Carmarthenshire, which was rebuilt in the late 14th century and served as the residence of the castle’s constable.

Barbicans

The approaches to gatehouse were also often further protected by structures known as barbicans. Miniature stand-alone fortresses, these were intended to provide extra layers of defence. In some cases, these fortifications are very impressive in their own right, as can be seen with the splendid barbican at Lewes Castle in East Sussex.

Water Defences

One of the best ways to improve the defences of a castle was to surround it with water, known as a moat. These hazards made it virtually impossible for besiegers to approach a castle’s walls without having to fill in the moat (often under fire) or by using boats. A particularly elaborate example of water defences can be seen at Caerphilly Castle in south Wales. The 13^th century citadel was encircled by two large artificial lakes, thereby turning the castle into an island.

Concentric Defences

The late 13th century saw the development of elaborate concentric castles which had multiple layers of defence. At Beaumaris Castle in Anglesey, the first layer of defence was the moat, followed by an outer ward and then an inner ward, with the outer wall overlooked by the inner wall. Therefore, if attackers stormed the outer defences they would be confronted by the defenders, who could rain down missiles onto them.

Docks

Garrisons could only resist sieges if they were adequately supplied with food and drink, if these ran out then even the best defended castle would surrender to besiegers. It was for this reason that many castles were situated adjacent to rivers or to the sea thereby allowing them to be provisioned by water. Edward I was careful to ensure that the new castles he built in the late thirteenth century to secure his conquest of north Wales, such as at Conwy, could be supplied by ships, to ensure that they could resist Welsh rebellions.

Arrow-slits

Castle garrisons were equipped with missile weapons such as crossbows and longbows to resist sieges. Extra protection was given to archers and crossbowmen by carving slits into walls and towers so that they could shoot their missiles at attackers in relative safety, as can be seen at Swansea Castle in south Wales.

Gun-ports

The development of gunpowder weapons in the Late Middle Ages meant that some castles had to be adapted to defend against this new technology. One method of doing this was to convert existing arrow-slits into gun-ports designed for the use of early guns. This can be seen at Carreg Cennen in Carmarthenshire, where an arrow-slit has been modified for the use of handguns and other small guns.

Hoarding

Early stone castles often incorporated temporary wooden defences known as hoarding. This was a covered structure placed on the edge of walls or towers to allow the defenders to have a better arc of fire at attackers, especially enemies who might approach the base of the fortification. This type of feature does not tend to survive as timber deteriorates much more quickly than stone, but an example of a reconstructed segment of hoarding can be seen at Caerphilly Castle in south Wales.

Machicolation

In the Late Middle Ages, hoarding was often replaced with a more permanent stone replacement known as machicolation. These were attached to the edge of the battlements of walls and towers and allowed defenders to drop objects onto the heads of attackers. A fine example of machicolation can be seen at the gatehouse of Bodiam Castle in East Sussex.

Dan Spencer is the author of The Castle at War in Medieval England and Wales. He  is an expert in late medieval warfare, particularly on the subjects of gunpowder artillery and castles. He has written a number of articles in academic journals as well as co-authoring, The Agincourt Companion (Carlton Books Limited, 2015). He is the main contributor to the website www.agincourt600.com and co-designed the Future Learn open access online course – ‘Agincourt 1415: Myth and Reality’. His knowledge of castles and warfare has also been enhanced by his experience of teaching the subject to undergraduate and international students at the University of Southampton.