Throughout the Middle Ages, engineers and armies developed a range of siege weapons designed to break through even the strongest castle defenses. These medieval weapons ranged from simple, yet devastating tools like the battering ram, to highly engineered machines such as the trebuchet and ballista. Each device served a specific purpose — whether it was to launch projectiles over high walls, smash through gates, or provide elevated platforms for soldiers to storm fortifications. Popular examples include the mangonel, siege tower, and catapult, all of which played key roles in prolonged battles for control of fortified strongholds. This article explores the most effective and iconic castle siege weapons used during medieval warfare, revealing the ingenuity and brutality of siege tactics in this era.
Ballista – Catapult Siege Weapon
The Ballista was one of the most important castle siege weapons whose shape was similar to that of a large crossbow. It worked on the same principle that a dart-throwing machine works, only on a much larger scale.
Heavy bolts, darts, and pieces of iron could be aimed at the castle with a Ballista. It was used in the ancient world as well but became widely popular during medieval times.

Mangonel – Catapult Siege Weapon
The Mangonel was another popular castle siege weapon that was quite similar to a catapult and was used to fire heavy projectiles from a large bucket attached to it.

It had an advantage over other catapults in that its design was simpler and thus it could be constructed easily. However, the Mangonel was not as accurate in hitting its target as a Ballista. Just like a Ballista, it was used in the ancient world but became more famous during medieval times.

Battering Ram – Castle Siege Weapons
Among the most common form of castle siege weapons were battering rams which could be made into various sizes and shapes. For instance, there were simple log battering rams, battering rams with flat heads, battering rams with iron or bronze heads, battering rams with actual ram’s style head, and others.
Sometimes a roof was used on the battering ram in order to protect the soldiers from incoming enemy missiles. This roof was called a penthouse. The use of battering rams was quite popular because they were very simple to construct and easy to operate. However, they could only be used once the castle gate had been approached.

*Castle moats, especially if the castle had a drawbridge were a very effective defense against battering rams.
Trebuchet – Catapult Type Siege Weapon
Various other kinds of castle siege weapons were also prevalent during medieval times. For instance, the Trebuchet siege Weapon was not very different from a catapult *Main difference the larger Trebuchet can throw heavy projectiles.

The trebuchet was mainly used to throw heavy stones at the outer walls and Gatehouses of the Castles to demolish them.

Catapult Siege Weapon
Catapults were effective weapons during a Castle Siege attack, to break down walls, throw burning missiles, rotting carcasses, even excrement and garbage*
Types of Catapults
*The most powerful Catapults were the mangonel and trebuchet siege weapons

Mangonel Catapults were also known as the ‘traction trebuchet’ could throw heavy objects for considerable distances *Distinctive with an arm with a large bowl shape at the end *Because of its power heavy stones could be thrown – but also rotting bodies and excrement!
Trebuchet
A trebuchet could be described as a counterweight throwing engine, a kind of giant wooden sling that was mechanized. The Trebuchet has its origins in the sling that originated in ancient China but its exact date of origin is unclear.
The Trebuchet was a very powerful siege weapon that could throw very large and heavy stones some distance *Famously the legendary Warwolf was the biggest Trebuchet ever to be built in history and used during the Scottish Wars of Independence. It was built on the orders of King Edward in 1304 as he laid siege to the Stirling Castle in Scotland.

Onager
Mangonels were also considered to be Onagers in some circumstances, the Onager siege weapons were created before the later superior Mangonel and launched projectiles from a sling.
Castle Siege Tower
The Castle Siege Tower was constructed from wood, siege towers were designed to align with the top of an enemy’s Castle walls and give attacking soldiers a way to breach the Castles walls or target battlement areas under protection.

Siege towers had small wheels that would enable them to be pushed close to castles walls, multiple siege towers could be used to overwhelm a castle’s defenses and they could also be used against damaged areas of the castle’s main walls or towers.

*Castle moats, especially if the castle had a drawbridge were a very effective defense against siege towers.
Castle Siege Weapons Summary
Castle siege weapons played a very important role in conquering a medieval castle. Without these weapons, it was almost unthinkable to defeat the army within the castle.

Thus, over the centuries, various new castle siege weapons were constructed with sophisticated techniques, although many of these castle siege weapons were also prevalent in ancient times. Their use, however, became particularly widespread during medieval times when a large number of castles were built.