# trebuchets vs walls

#### Olleus

Guys- do the math.
Trebuchets didn't kill people- the things the trebuchet HIT killed people. Its a physics problem. Ever seen one of those thingies with the hanging steel balls that transfer momentum back and forth? That trick only works because the steel balls are So Very Hard that the energy transfer is extremely efficient. Build one with rubber balls and its not nearly as effective.

Trebuchets were not aimed at people, but at walls and buildings. A Stone hitting another stone is a near perfect trasnfer of energy.
If a stone from a trebuchet hit the parapet of a castle, The other side of the stones making the parapet would shatter into a thousand sharp shards of stone.

They DID bring down walls, even very thick walls, because of HOW thick walls were built. Thick walls were made by building two THIN walls a dozen feet apart and filling the space between with rubble. If you shattered out a section of the outside stone wall, then the rubble interior would SPILL out like so much sand. This would leave a nice hole thru which your next shot would sail to break out an even larger section of the inner wall.

The resulting pile of spilled rubble would form a Ramp up to the breach. This is how jerusalem was taken, thru breaches in the several sets of walls created by roman ballista.

Cannon did the exact same work, just a lot faster with a much more portable device. Only then did castle walls stop being tall ( hard to climb ) and start being LOW and ridiculously thick earthen works faced with stone.
I'm not sure why people harper on about energy so much. It's far more to do with momentum transfer or even pressure exerted. You could transfer as much energy as a trebuchet does by lightly warming a large section of wall, but it would have very little destructive impact.

wigglywaffles

#### kazeuma

The plan was not to knock down the wall - it was to kill the people inside, frighten the defenders, spread disease, and to start fires on the inside. And there is the added fear factor - an army marches up to your castle, surrounds it, and then spends a day building a massive catapult - so huge that you can see it from inside the city wall - the psychological effectiveness might make the defenders think about surrender.

#### wigglywaffles

Guys- do the math.
Trebuchets didn't kill people- the things the trebuchet HIT killed people. Its a physics problem. Ever seen one of those thingies with the hanging steel balls that transfer momentum back and forth? That trick only works because the steel balls are So Very Hard that the energy transfer is extremely efficient. Build one with rubber balls and its not nearly as effective.

Trebuchets were not aimed at people, but at walls and buildings. A Stone hitting another stone is a near perfect trasnfer of energy.
If a stone from a trebuchet hit the parapet of a castle, The other side of the stones making the parapet would shatter into a thousand sharp shards of stone.

They DID bring down walls, even very thick walls, because of HOW thick walls were built. Thick walls were made by building two THIN walls a dozen feet apart and filling the space between with rubble. If you shattered out a section of the outside stone wall, then the rubble interior would SPILL out like so much sand. This would leave a nice hole thru which your next shot would sail to break out an even larger section of the inner wall.

The resulting pile of spilled rubble would form a Ramp up to the breach. This is how jerusalem was taken, thru breaches in the several sets of walls created by roman ballista.

Cannon did the exact same work, just a lot faster with a much more portable device. Only then did castle walls stop being tall ( hard to climb ) and start being LOW and ridiculously thick earthen works faced with stone.
then why are there so few records of thick walls being knocked down by trebuchets? I mean I did find some stories of wooden walls getting knocked down but stone/rammed earth? No. Even the super heavy ones were more made to provide supressing fire or to destroy buildings inside the wall

#### Ichon

then why are there so few records of thick walls being knocked down by trebuchets? I mean I did find some stories of wooden walls getting knocked down but stone/rammed earth? No. Even the super heavy ones were more made to provide supressing fire or to destroy buildings inside the wall
Partly because very few strong fortresses were even attempted to be taken by storming/siege assault. Most defenders surrendered or those laying siege gave up before they finished building the siege engines due to disease, change of seasons, logistics issues, enemy relief army, etc.

There are a few descriptions of battles where the enemy surrendered as soon as the besiegers finished building the siege engines and even a smaller amount of accounts of sallying out to destroy siege engines. I don't think there are more than a handful of medieval accounts of counter battery fire or walls being reduced to rubble purely by the work of trebuchets though with the introduction of cannon we do start to see those sort of accounts.

The cost and effort to build a trebuchet would be wasted if they didn't do something and recreated trebuchets are actually fairly accurate once built (on the scale of being able to hit a 30 foot high wall repeatedly within a 10 foot wide section). The main problem was hitting long or short due to the various weights of the projectile but relatively low skill but high in labour things such as balancing two projectiles on a beam and carving off pieces until they balanced helped there but also contributed to the expense- not only was the trebuchet expensive to build, every shot if going for accuracy had to be built essentially by hand when it was just large stones.

Obviously not every single siege would even see the besiegers attempting to make a hole if they built a trebuchet- just the fact they built it and put it into the fight contributed to the siege with the stress of the bombardment and the trebuchet could be much busier if not needing every projectile to be weighed and measured.

wigglywaffles

#### Olleus

Even the super heavy ones were more made to provide supressing fire
I don't buy that. Roman era ballista, sure. But trebuchets are simply far too slow to shoot to be useful surpressing fire

Ichon

#### Willempie

I don't buy that. Roman era ballista, sure. But trebuchets are simply far too slow to shoot to be useful surpressing fire
Not only that, but you are not going to go through all the trouble of building one (which is a bit more complex than the average DIY) and obtaining stones of appropriate size and weight, to then decide to just annoy the other side with it.

#### heavenlykaghan

I don't buy that. Roman era ballista, sure. But trebuchets are simply far too slow to shoot to be useful surpressing fire
Where did you get the idea that trebuchets have a slow rate of fire? We are not talking about the counterweight trebuchet here.

Here is the Miracles of St Demetrios recording an Avar siege in the late 6th century A.D. These siege engines were explicitly described to be pulled by ropes, which mean it is a trebuchet.

"On being discharged they sent up many great stones so that neither earth nor human constructions could withstand the impacts....For what else might one term these immensely large stones?"

"they were four-sided; they rose from broader bases to narrower tops on which there were massive cylinders, their ends sheathed with a thick layer of iron; to them there were attached lengths of wood, like the beams of a large house, and these had slings; and when these (the slings) were raised up, they sent out rocks; the rocks were large, the shots frequent..."

"Thence the enemy captured effortlessly a great many of the Roman cities"

The Byzantines themselves not only commented on the large size of these rocks, but also the frequency of its shots. If anything, the trebuchet took less time than torsion weapons to fire and its destructive capabilities certainly surpassed anything the Byzantines had and that was why it replaced the traditional siege machines in medieval time.

#### Willempie

Where did you get the idea that trebuchets have a slow rate of fire? We are not talking about the counterweight trebuchet here.
Depends on who you talk to. I was taught that the trebuchet is the catapult that uses counterweights. The catapult that uses torsion is the onager and the one that is being pulled by people is the mangonel. I have interpreted the discussion to be about the counterweight one.
Apparently in every country they use these terms in their own way.

#### Olleus

Where did you get the idea that trebuchets have a slow rate of fire? We are not talking about the counterweight trebuchet here.
People in the rest of the thread, including in the opening post, where referring principally to counter weight trebuchets. So that's what I was discussing...