Got a Real-World Weapon, Armour or Tactics Question? Mk. XXX

[snowblizz]

The big innovations of star forts is the composition of the walls. Against gunpowder weapons, tall walls of thick stone are incredibly vulnerable. Star forts evolved low walls with lots of packed earth to absorb cannonfire. However, against an opponent that lacks weapons of gunpowder, the older style of wall is superior. The height (and sheer sides) not only makes it far harder for people to get over the walls, but gives a commanding position for observation. Older castles were well designed to avoid excessive blind spots and pretty much every tactical factor conceivable to the designer - siege warfare is a brutally Darwinian process and it would not be uncommon to start remodeling if you heard about some other castle falling and looked into the vulnerability that allowed it.

To be pedantic castles weren't necessarily built with solid stone throughout the thickness of the wall. You would normally have an inner core consisting of dirt, stone, gravel, sand or whatever detritus you had lying around. Also even in a starfort the walls are incredibly vulnerable to cannonfire. They can't withstand it either. That is why the trace d'italienne aka bastion style was transitionary. No wall at any thickness could resist the relentless pounding if iron cannonball that could be targeted with much greater precision than previous torsion artillery to continuously smash at the same small part. Eventually the only solution was to bury the entire fort underground, so you can't actually hit the walls directly. Since that isn't practicable if you want shot back you bury the fortress walls underground while they are still overground. The earth ramparts are not actually part of the walls themself. They are separate structures to protect the walls by creating a unyielding absorbing barrier that stops cannons form actually being able to hit the stone walls of as starfort.

One of the funnier things is when they started building coastal forts out of bricks, with really really thick brick walls. But still it's just bricks. The bricks would crumble under the pounding of cannonball, but they acted a lot like earthen ramparts did absorbing the impact energy. And just when everybody had upgraded their coastal forts this way someone invented reliable impact fuses and explosive shells making guns where the shell would bury into he brick work and explode it to bits. Decades of fortification work all useless.

That doesn't quite eliminate the issue. You can use the curvature of one of the towers to shield yourself from the other towers.

And the same problem exist in starforts, they are at their most vulnerable at the tip of each point. Which is also exactly where siege trenches aimed towards. The strongest part, the one most covered by gunfire is close to inner angles of the bastions, which isn't surprising as the biggest danger of one is that an enemy takes it in a escalade. Although it's a bit more complicated to do than I make it sound. A start fort in peculiar way could be said to apply the principle of the high wall in the horizontal plane instead. Diagrams of startforts (when showing a top-down view) seldom visualises the broken up nature of the slope with trenches, dugouts etc that breaks the "slope" from the walls down to ground level. This and other reasons is why there are no impregnable fortifications. And in the case of starforts, Vauban even claimed to mathematically be able to determine how long any fort could be expected to hold given the design, and troop complements involved. There was a certain degree of inevitableness in the digging of trench works and besieging of a starfort. But this wasn't a weakness per se, it was to a degree a feature. Forts were never expected to stand forever. They existed to bottle up an attacker for enough time that a response could be mustered further away to relieve the fort.

In a pre-gunpowder world, there's also nothing you can do there to affect the wall itself. A ram or bore needs space to operate and is extremely slow, mining operations are started much further away to allow for larger work crews, and those are the only personal-scale tools that can do anything at all to a castle. Even if you tuck in that close and successfully avoid attack, there's absolutely nothing you can do except wait for the cover of darkness to run away.

People actually did attack walls with person level items, crowbars, picks, etc. There was a famous siege during the crusades where the crusaders did so despite the relentless bombardment from above. But the diagram also misses the awnings castles would have had to support dropping stuff down on such people. Or various murder holes etc etc etc. Castles builders knew about these problems and would add measures, we only see the naked stone walls on castles nowadays, that is usually not how they looked as they lack the integral wooden structures added on top of walls to extend arcs of fire etc into blind spots. Trying to work at the base of the walls with tools, which did happen, is as you suggest very very difficult and will require a lot of time. It is also for such reasons you have sally ports allowing you to safely deploy a small team to take out such bold interlopers while the majority of the enemy are held back by the fire from the walls and the various features that make closing in to castle difficult for attackers..