Blog Post 5
Siege mining, if used correctly, was one of the most effective and successful ways to attack a castle. All of the siege weapons that I have talked about so far consisted of destroying castle walls from above. Mining attempted to destroy castle walls from beneath. There were a couple different ways to mine an enemy castle. One was to build a mine that went all the way under the castle wall and surfaced inside the castle. This provided access to the inside but usually led to a sword battle where the defendants would have the upper hand. The second way was to dig a tunnel below the walls and then collapse the tunnel which would collapse the walls. The third way was called sapping, which was digging directly around the walls and collapsing them.
The least popular of the 3 types of mining that I mentioned was the first. Digging tunnels all the way under the walls and into the castle was probably the least effective way of mining. This usually didn’t work well because there would be a whole army waiting on the inside that would kill the miners with ease.
Sapping was a viable way to attack a castle. Sappers would go directly up against the castle wall and begin digging down against the wall until they got before the foundation. Then the would undermine the foundation and hopefully collapse the wall. Under certain conditions it could be quite effective. Sapping was most effective when used to collapse the corners of castles. The corners were the weakest part of the wall and the easiest to collapse by sapping. Later on castle began to be built with rounded edges to prevent sapping. The other disadvantage of sapping was that the sapper would be completely exposed to enemy fire and could be shot before they could collapse the wall.
The most effective type of siege mining was a mixture of the first two. They would try to collapse the walls like in sapping but would use tunnels like the first. In this type of mining armies would employ skilled miners to build a tunnel starting at their camp and ending just below the enemy’s castle wall. Once they would reach the wall they would dig under the foundation and replace foundation supports with wooden beams. Then when they had replaced enough supports with wooden beams they would set fire to the the beams. They would then leave the tunnel and wait for the fire to burn the wooden beams and collapse the walls. This was the safest and most effective type of mining because you never come into contact with the enemy until their walls are collapsed and you are ready to fight.
When collapsing the castle’s walls was successful it usually led to the surrender of the castle’s occupants. They knew they didn’t stand a chance once their walls were taken out. There were ways to prevent mining though. The best way to prevent mining was counter mining. This consisted of digging a tunnel below the other tunnel and collapsing their tunnel before they could collapse the walls. The other way to defend against mining was in the design of the castle. Removing sharp corners and replacing them with rounded edges strengthen the walls and made them harder to collapse by mining. They also would add buttresses that enlarged the footprint of the wall. This made the walls much harder to collapse as well.
Medieval Siege Tactics. 11 March 2005. 2016 5 December. <http://www.timeref.com/castles/castsiege.htm>.
Bradbury, Jim. The Medieval Siege. Woodbridge: The Boydell Press, 1992.