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 defenses.
Notable among such defenses was the construction of moats which were dug all around a castle.
The moat was dug as a fairly deep and wide ditch.
The key purpose of a moat was to stop the enemy from marching directly on to the walls of a castle.
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.
Many different types of moats were typically used in medieval castle.
The most common by far was the kind of moat which was filled up with water and ran all around a castle’s boundary.
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.
Another type of moat was the dry moat – such a moat was a huge ditch set up with sharp wooden stakes and other obstacles.
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.
During the medieval ages, the most common method of breaching a castle was to launch a frontal assault and through sheer numerical superiority, force ladders against the castle walls.
The attacking force would then scale the walls and over them into the castle.
Another method was to surround a castle and then used battering rams to break into the entrance of the castle.
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.
The moat was a superior defensive device in that it effectively rendered all such attempts futile.
By surrounding the castle walls all along with a moat, the defenders essentially made it impossible for the attackers to bring their ladders, battering rams or tunneling equipment near the castle walls without suffering huge losses and facing many other difficulties.
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.
They eventually evolved into regular and highly developed moats used from 12th century onwards in medieval castles, especially by Plantagenet monarchs in England.