As some of you may have guessed by my first MOC ever posted here, I am very interested in the Vauban Forts of the Napoleonic Era. I had been working on a tutorial on the subject on and off since I joined, but since Horry beat me with his fantastic tutorial I have cut most of mine as to avoid redundancy and thus this tutorial will focus only on outworks - defences constructed beyond the main fort, designed to to engage the enemy away from the main works for various reasons: to protect the main fort from enemy field batteries, increase general firepower, fortify a weak area, or simply to extend their control further in that direction. Where possible, pictures are links to real life examples. C&C welcome.
Welcome to Fort Carillon, a fictional Napoelonic Era fort. Built in the Medieval Ages to protect the mouth of a vital waterway, it once stood as a mighty castle. But with the invention of gunpowder in the thirteenth century, it has by necessity been modified over the past centuries to better suit its purpose - ramparts lowered, walls thickened, bastions and cannon emplacements built. Now, with rumors of a coming war, the commander has initiated a series of projects, with the singular aim of strengthening the fort's somewhat lacking offensive and defensive capabilities through the creation of outworks.
Our first, most obvious step is to create a glacis. The glacis, the natural result of the evolution of walls (by Horry), was an artificial earthen slope that surrounded most Vauban fortresses. It functioned to shield the walls from direct cannon fire, such that the walls could not even be fired upon until an attacker had passed it: and it gave the defenders a direct line of fire, thus they could fire upon attackers all along the glacis without changing their firing angle. The ditch formed between the glacis and the fort had its own uses.
In permanent fortresses, the ditch would often be lined in stone. Its inner face was called the scarp, while the outer was called the counterscarp, along which a covered way was often built. This was a high walkway slightly below the top of the glacis that gave the soldiers a safe firing area as well as a line of communication around the fort during a battle.
In some fortresses such as the Castillo de San Marcos, the ditch could be flooded before a battle through floodgates. There could be other defensive mechanisms worked into the ditch, which we will examine now: the caponier and counterscarp battery.
Realizing the entryway to be a weak point in the fort defenses, the commander has ordered the building of a caponier to protect the ditch before the entrance. A caponier was essentially a bunker that was sunk into the ditch. It could serve as a simple secured route to an outlying outwork such as a redoubt or bastion as well as to sweep the ditch to prevent the enemy from assembling there. Its armament would not exceed several light guns, and most often consisted of only a few rifle ports (by Horry) for the soldiers. To avoid destroying each other, they were placed either at corners or singly on a wall. They were susceptible to plunging (high trajectory) fire from enemy cannons, thus they were often built with rounded tops or covered in earth.
A counterscarp battery (not built into Carillon) was a battery built into the outer face of the ditch for which it was named. It would be accessed by a tunnel. It had an advantage over the caponier in that it was invulnerable to plunging fire, but its location outside of the ditch made it easier to undermine.
In an effort to further protect the entry, (though this time it is protection from direct bombardment, not infantry) a ravelin is built in front. The ravelin is an evolved form of the demilune (half moon - this should help you realize its shape) outwork, which takes the shape of an arrowhead pointing outwards. The ravelin's guns cover the approaches to the curtain wall, while its own sides are covered by those of the main fort bastions. In general, the inward face of a ravelin will be open so that if overtaken it will not offer any shelter to the enemy.
The glacis has been expanded to accomodate the new construction. This will happen for all future additions as well. Note that the ravelin could be used not used only to fortify the entrance but as an additional battery, for example in the inspiration for Carillon's "base model," Ticonderoga.
While the ravelin was being constructed, the fort was attacked by the enemy navy. Though Carillon survived, this attack exposed a major flaw in the fort's positioning - it's right was too far away from the river, thus many of its shots missed their mark. Rather than demolish the existing fort for relocation, the commander has ordered the building of a hornwork, to provide a larger base for seaward artillery.
The hornwork is one of the more complicated structures we will go through in this tutorial. Before we begin we have to define the term demi-bastion: a bastion with only one face and one flank (a regular bastion has two of each - it's as if one of the angles had simply been flattened).
What you see above has more parts to it than just the hornwork, which is simply just the largest, central structure there (the rest are supporting ravelins). The hornwork had two demi-bastions (the "horns" for which it was named) at its outermost edge which led straight back to the fort. These long edges were always protected by the bastions of the main fort, and at Carillon two extra ravelins were built at its base to increase the defensive power.
The expanded form of the hornwork was the crownwork, which had a full bastion bordered by a demi-bastion on both flanks.
Down the road apiece we have built our final outwork - a redoubt, to intercept the enemy before they reach the fort.
The redoubt was a semi-independent outwork built to defend soldiers outside of the main fort complex. It differed from, say, a ravelin in that it was completely enclosed. Most redoubts were simple triangular, square, or pentagonal enclosures made of stone or earth. However, the one built at Carillon is similar to those at Niagara (see the linked picture), thus it is much more elaborate.
So there you have it, the finalized Fort Carillon.
One thing I have tried to emphasize throughout this tutorial is that there is no set formula for creating a fort - though you will see many perfect pentagonal, square, and star (as was the Renaissance ideal) forts, this was more often than not not the case. Rather, the fort's design would often be formed on the basis of its natural surroundings.
I hope you have enjoyed this tutorial, if there is anything you'd like me to add (this tutorial is not at all comprehensive, but I don't think any more would be necessary - for a more complete diagram (albeit in French) click here), correct, or discuss, feel free. The LDD file can be downloaded by clicking here.
Thanks for reading, have a good night. Cheers!