The Importance of Siege Weapons in the Medieval Era: The Trebuchet

Siege Warfare was a medieval military operation involving the surrounding and blockading of a town, castle or fortress by an army in the attempt to capture it.1 Siege weapons first appeared around 20,000 B.C.E in the form of bows and slings.2 These ranged weapons necessitated the building of fortifications, or walled defenses, around population centers since strictly melee warfare would now become much more dangerous for the foot soldiers. However, these fortifications could not be constructed until a radically new technology was invented: agriculture. A debate around this has formed among scholars with one side arguing that the need for fortifications caused the invention of agriculture and the other side believing that agriculture was invented and then people settled into sedentary communities. Personally I believe in the latter argument due to the fact that the first fortifications we know of didn’t pop up until around 7,000 B.C.E in Jericho. This 13,000 year gap where people obviously still needed fortifications but still remained nomadic leads me to believe that agriculture had to be invented before people settled.

After these fortifications were commonplace one of the first siege strategies was escalade. This involved a group of people attempting to scale the walls of the fortifications while archers behind them laid down covering fire. This strategy was ineffective over about 10 meters which is why ancient cities’ walls were so massive, some over 20 meters tall.


By 3,000 B.C.E bettering rams were common place as seen in this picture of a primitive battering ram with the people inside covered from defending fire.

Finally, by 1,800 B.C.E siege warfare was commonplace and advanced, with the use of siege towers and ramps, more advanced battering rams, and sapping, which is a strategy where the attackers attempt to drill through the defenders walls.

Now to give a brief overview of medieval siege weapons.

Most of these weapons were largely the same, just advanced. Some examples of this include better battering rams, siege towers, and escalade machines.


However, a new invention that showed up in medieval times was the ballista. This was essentially a very large crossbow and generally was used for defense as opposed to offense due to its ineffectiveness against walls but its decimating power against people.3


Finally another major new invention was the trebuchet. The trebuchet first was seen in China between the 3rd and 5th centuries and made its way Europe via the Arabs in the 9th century.4 This version was a kind of trebuchet called the traction trebuchet and worked instead of with a large amount of man power pulling down on ropes to propel large projectiles towards the defending city. These trebuchets usually took a team of 40-250 men but could have as many as 1200.


Due to its inherent inaccuracy with the variability of human strength the traction trebuchet was eventually replaced with the counterweight trebuchet in the 12th century. This improvement focused on adding a large counterweight to the end of the beam and uses gravity as the main pulling force to hurl large projectiles towards and over walls. This design gave the trebuchet a large increase in accuracy due to the pulling force being constant since both the counterweight and gravity are fixed.

During my research I found a scholarly debate about the actual uses of trebuchets in medieval sieges. Kelly DeVries, professor of history at Loyola University Maryland believes that “[trebuchets were] able to hurl a projectile up to 300 meters but the steep arc of [their] flight limited effectiveness against fortifications. This has led to the idea that trebuchets were used mainly to launch items over the walls, including diseased animal carcasses or the heads of captured men.”5 Another argument against the use of trebuchets on walls comes from the fact that if the stones broke on impact they would do very little damage so stones often had to be quarried hundreds of miles away and then taken to the battlefield, a very energy intensive task.6

The other side of the argument said that of course trebuchets were used to break down walls, which was one of their main purposes.

Donald Hill combines these two beliefs into one where he believes that “light trebuchets were used to throw missiles into the city, whereas the heavy trebuchets were used for attacking the walls,” a thought shared by Scott Farrell.7

After concluding my research I tend to lean towards Hill and Farrell’s belief that the attacking battlefield consisted of both heavy and light trebuchets where the light trebuchets were used to lob objects over the walls while the heavy trebuchets stood farther back and were used to fire at the walls themselves. I believe this because practically there doesn’t seem to be much of a reason to fashion a machine that can fire 300-400 lb. rocks hundreds of yards if it was not being utilized against the main barrier between the attackers victory: the walls.



  1. Linda Alchin, “Siege Warfare,” Siteseen Ltd. last modified March 2018, accessed December 10, 2018,
  2. Paul Kern, “Fortifications and Siege Machinery,” Ancient Siege Warfare, (Indiana University Press, 1999), 9-22.
  3. C. Gravett, R. and C. Hook, Medieval Siege Warfare, ed. Martin Windrow, (London: Osprey Publishing Ltd, 1990).
  4. “[Weapons 101] Trebuchet – Traction & Counterweight – Medieval Equipment,” Military History Visualized,last modified August 26, 2016, accessed December 10, 2018,
  5. Kelly DeVries, “Q&A: When and where was the trebuchet invented?” History Extra, last modified August 1, 2013, accessed December 10, 2018,
  6. [Weapons 101] Trebuchet – Traction & Counterweight – Medieval Equipment.
  7. Scott Farrell, “Arms and Men: The Trebuchet,” Historynet, last modified September 6, 2006, accessed December 10, 2018,


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