Sappers: Specialist Miners in a Medieval Castle Siege

During a medieval castle siege, a unique set of miners were employed to dig under the castle walls in order to gain entry.


a medieval sapper mining under a castle to colla1

These specialist miners were essential to the success of a siege and were known as “sappers”. Their training was intense and they were highly skilled in the use of picks, shovels, and explosives to break through the thick castle walls.

In this article, we will explore the role of sappers in a medieval castle siege.

A Trebuchet Catapult Siege Attack on a Castle

What are Specialist Miners?

During a medieval castle siege, specialist miners were individuals trained to dig under the walls of the castle. These miners were employed to try and weaken the walls, allowing the besieging army to breach them and gain access to the castle.


a medieval sapper mining under a castle to colla3

“Medieval sappers were among the most skilled and daring of all military engineers, using their expertise to tunnel under enemy fortifications and undermine their walls.” .”

Kelly DeVries, Professor of History at Loyola University Maryland and author of “Medieval Military Technology

They would dig tunnels under the castle walls, collapsing them when they got close enough to the surface. As a result, they were also known as sappers or miners. The job was dangerous and required special training, as the tunnels had to be dug quickly and with precision.

The miner’s tools were simple, just shovels and picks, but their work was essential for gaining access to a castle.

a medieval sapper mining under a castle to colla

How Were they Trained?

Specialist miners were trained to dig tunnels, also known as saps, that would allow a besieging army to break through a castle’s defenses. This highly specialized skill was learned by miners in their native countries, such as Italy, France, and Germany.

These miners were often well-trained and experienced, having practiced their craft for many years. Their main task was to dig tunnels under the walls of the castle and to construct various tools and devices that would facilitate their digging.

“The use of sappers in medieval warfare was a significant development, allowing armies to break through seemingly impregnable fortifications and gain strategic advantages.”

Ian Heath, military historian and author of “The Medieval Siege.”

They would use fire or gunpowder explosives to weaken the walls of the castle, and set up siege engines to take down the defenses. They also had to learn how to build and maintain defensive barriers around their tunnel entrances, as well as how to build reinforced shelters and tunnels inside the castle.

In order to be successful at their job, miners had to understand and anticipate the enemy’s tactics and strategies. As such, they had to be highly observant, patient, and skilled in their craft.

Siege orleans canon

5 Good Books about Medieval Sieges


“The Medieval Siege” by Jim Bradbury
This book provides a comprehensive overview of siege warfare during the medieval period, including the role of sappers in undermining fortifications.

“Medieval Military Technology” by Kelly DeVries
In addition to covering medieval sappers, this book explores a wide range of military technologies and their impact on medieval warfare.

“The Art of Warfare in the Age of the Crusades: Equipment, Tactics, and Techniques” by Western Michigan University Medieval Institute
This book delves into the tactics and equipment used by medieval armies, including the use of sappers and their role in siege warfare.

“Oxford Encyclopedia of Medieval Warfare and Military Technology” edited by Clifford J. Rogers This multi-volume encyclopedia provides a wealth of information on medieval warfare, including the tactics and technology used by sappers.

“Siege of Malta, 1565: Translated from the Spanish Edition of 1568” by Francisco Balbi di Correggio
This primary source account of the Siege of Malta in 1565 provides insight into the tactics and techniques used by sappers during the medieval period.