Castle Moat Defense

Medieval Castle Warfare

Medieval castles were mostly used as military fortifications sufficiently equipped to withstand a potential attack from an enemy. As a result, these castles were secured with many layers of defense. Notable among such defenses was the construction of moats which were dug all around a castle.

Castle Moat Fortress inSwitzerland

The moat was dug as a fairly deep and wide ditch. The key purpose of a moat was to stop the enemy from attacking the entrance and walls of the castle directly with powerful siege weapons such as battering rams.

Battering Ram Siege Weapon

The moat also stopped enemy attackers from using siege towers against the castle’s curtain walls, and it prevented miners from digging underneath the castle walls to collapse them using a wooden framework that was then set alight.

Siege Tower and Battering Ram

Siege tower

Muiderslot Castle Moat

As a defensive structure, the moat was very effective in nullifying many conventional methods of breaching a castle’s boundary walls, thereby giving castle defenders a vital extra layer of defense.

Medieval Castle Moat Types

Many different types of moats were typically used in defending a medieval castle. The most common by far was the kind of moat that was filled with water and ran around the castle’s boundaries. Such a moat made it impossible for an enemy to directly scale the castle walls with ladders or to attempt the tunneling of the walls.

Medieval Castles Defences Moat

Another type of moat was the dry moat, such a moat was a large ditch filled with obstacles such as sharp wooden stakes, anything that would slow down attackers and allow the castle defenders time to fire missiles upon them.

Example of a Dry Moat at Dourdan Castle

An approaching enemy had to carefully pass through these obstacles and doing so on horseback was virtually impossible. A hybrid type of moat, called a segmented moat, was also frequently used in medieval castles where a portion was filled with water while the rest was set up with wooden stakes.

Moats were also used to protect different segments of a medieval castle. A moat separating an inner and outer segment of a castle in this way was called a cross ditch.

Defensive Use of Moats

During the medieval ages, the most common method of breaching a castle was to launch a frontal assault and through sheer numerical superiority overcome the castle walls. Another method was to surround a castle and then used battering rams to destroy sections of the curtain wall or batter down the entrance.

Siege Tower

When both of these methods proved inviable, the attackers would attempt to tunnel under castle walls and try to collapse a portion of these walls in order to force a breach.

mine shaft g59485612b 640

The moat was a superior defensive device in that it effectively rendered all such attempts futile.

A Medieval Castle Being Defended Under Siege

By surrounding the castle walls with a moat, the defenders essentially made it impossible for the attackers to bring their siege towers, ladders, battering rams, or tunneling equipment near the castle walls without suffering huge losses and facing many other difficulties.

Medieval Castle Moat Attack


Moats were a popular feature of the early medieval castles constructed by the Normans in 11th century England. These early moats were fairly basic, meant to protect the boundaries of motte-and-bailey castles.

Motte Bailey Medieval Castle

They eventually evolved into regular and highly developed moats used from the 12th century onwards in medieval castles, especially by Plantagenet monarchs in England.

medieval Castle moats

Towards the late medieval period, moats were either used in a very complex form or were abandoned altogether due to the advent of gunpowder weapons.

Medieval Gunpowder Weapons