Ancient & Medieval Terms - Fortifications

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agger: Siege mound, ramp, or terrace built out of earth, stone, timber or debris from demolished buildings. It allowed attacking armies to bring heavy machinery, such as siege towers, closer to city walls and overtop them.
arbalestina: A cross-shaped opening ina wall from which to shoot with a crossbow
bastion: An earthwork projecting from a fortification in order to flank the curtains.
battlement: Defensive wall
boulevard (or bulwark): Addition to town or castle defences in the form of a projecting fortification (barbican or bastion). Usually low, semicircular defences built before the main gate.
brattice (or breteche): A breastwork, parapet or gallery made of wood. Term has been used for the central wooden tower of a motte-and-bailey castle, or wooden fortifications at the gate. When a breach was made in the castle wall, a brattice could be built within to serve as a new temporary defence.
The term also applies to the overhanging wooden hoardings and covered passages that were built at the top of castle walls, supported by a series of corbels called machicoulis. They could be entered from the walls, and featured holes for dropping stones, hot water (or oil) and missiles on the attackers. This was later the function of the stone built machicolation.
bray (or braye): A low wall outside the ramparts to prevent the enemy from approaching them.
broch: In medieval Scotland, a type of tall, round, stone tower first employed by the Picts.
cat: Also called sow, mouse, tortoise or weasel. Mobile roofed platform or hut used in siege warfare to give cover to the attackers, who could creep it close to a defensive wall. It was sometimes attached to the wall with iron nails. Animal hide was often used on the roof as a protection against fire. Especially useful in covering mining activity at the foot of the wall.
In 1218 de Montfort made one of iron and steel which housed 400 knights and 150 archers.
chemise: Outer wall surrounding the keep of a castle with a raised platform at the back that could be reached from the keep by a postern or drawbridge.
crannog: Irish term for an artificial island created in a lake for use as a refuge and fortification.
crenellation: A toothed effect along the top of battlements (defensive walls), with gaps between each vertical "tooth". The stone teeth were called "merlons" and the openings "crenels" or "embrasures".
Crenellation often fronted a wall walk, providing protection and openings for use of weapons.
Crenellation became the criterion to determine the level of fortification, and by the 12th century a licence was required to crenellate.
donjon: Castle keep or separate central tower. Term derived from Latin for lord.
gulai gorod: Russian moving fortress, comprised of wagons and mobile defensive screens to protect its defenders from horse-archer enemies.
hoarding: Wooden defence structure used in siege warfare. When siege was imminent, many fortifications had their roofs removed and hoardings were added to towers. Also when attackers brought siege towers up against fortifications, it was frequently necessary to raise the height of the walls and towers by constructing hoardings above them. (see also brattice)
machicolation: Projecting stone gallery on the wall or tower of a medieval fortification, supported by a row of corbels projecting from the wall. It replaced the earlier wooden brattices or hoardings. Its main purpose was to protect defenders who used the slots below for dropping objects onto attackers at the foot of the wall. The word originally referred to the openings in the floor, but later came to mean the whole structure. Machicolation developed in late 12th century.
meutriere (or murder-hole): Small hole in defensive wall or floor through which weapons could be fired (particularly opening into an area cut off by a portcullis, in which attackers were trapped).
motte-and-bailey: Castle with a tower on a natural or artificial mound (motte) and a courtyard (bailey) on a lower level, with the motte serving as the main defence. Much variety in basic design: some had two mottes or two baileys, some had a keep, others did not. First appeared as Frankish defences against the Vikings. Quick and cheap to build and useful in emergencies. Many were raised in Norman conquest of England and Ireland.
portcullis: Old French "porte coleice" = sliding door. A gate or grating that could be raised and lowered rapidly, forming part of a defensive gate. Probably introduced around 1100. Strongly built of wood or iron to resist attack. Often the lower edge had points for striking attackers as it fell. Often built at entrance and exit of a gatehouse so attackers could be trapped between the two and shot at from meurtriers. A portcullis moved in slots built in the doorway and was usually worked by pulleys in a chamber above the doorway.
rath: Medieval Irish term for a native fortification, usually a stone ringwork, in existence before introduction of castles to Ireland by the Normans.
ringwork: Simple, approximately circular bank-and-ditch formation usually employed for small compact enclosures.
wagenburg: (German "wagon-fortress"). A mobile fortification of early 15th century. Consisted of a number of large, often armoured, horse drawn wagons loaded with weapons and fighting men which were moved to a strategic position on the battlefield to form a formidable mobile fortress. Crews consisted of crossbowmen, handgunners, halberd- and flail-men. Provides strategic mobility.