Bastion Fort

A bastion fort is a fortification in a style that evolved in Otheia after Mages had come to dominate the battlefield. The fortress style is common to all states of the Augkarate. It was first seen in the mid-first century in Easu. Some types, especially when combined with ravelins and other outworks, resembled stars, and as such are known as Star Forts.
The design of the fort is normally a polygon with bastions at the corners of the walls. These outcroppings eliminate blind spots, and allows fire along the wall from positions protected from direct reprisals. Some forts also feature cavaliers, which are raised secondary structures based entirely within the primary structure of the wall itself, designed to increase the range of the Mages' projectiles.
=== Origins ===
The direct predecessor to the Bastion Fort were the old castles of the Age of Kings and the Warlord Period. These are usually located on high hills and have high walls and towers to facilitate shooting arrows at the enemy. To besiege such a fortress, the attackers must either batter down the gate, or climb the walls of the fortress with ladders.
These verticle, thin walls were vulnerable to a Mage, who could knock down the wall with a few thrown stones. Contrastingly, bastion forts are low structures, with numerous triangular bastions designed to cover one another, and a ditch. To counter the projectiles thrown by a mage, the walls of these fortresses were made lower and thicker to better absorb the damage. To combat infantry, who could now more easily scale the walls with ladders, the ditch was widened considerably, so that the enemy would remain exposed to the defenders from an elevated position, including enfilading fire from the bastions.
The earth removed from the ditch was piled onto the far side as an artificial slope, called a Glacis. This is designed to deflect thrown projectiles and cannonballs aimed at the lower part of the wall intending to create a breach. Outlying structures such as ravelines, hornworks, crownworks, lunes, tenailles, or even other, smaller forts could be added within or even beyond the ditch to magnify the defensive potential of the fortress, b further protecting the main wall, and providing positions for defensive artillery and mages of their own.
Bastion forts are built from many materials, such as stone, earth, or brick. Brick is typically preferred for its low relative cost and its energy-absorbing aspects.
==== Slopes ====
When the Battlemages came into military strategy in the first century, the response from military engineers was to arrange for the walls to be embedded into ditches fronted by earthen slopes, so that they could not be assaulted by direct fire and to have the walls topped by earthen banks that absorbed and largely dissipated the energy of plunging fire. Where conditions allowed, the ditches were cut into the native rock, and the wall at the inside of the ditch was simply unquarried native rock. As the walls became lower, they also became more vulnerable to assault.
==== Dead Zone ====
The rounded shape that had previously been dominant for the design of turrets created "dead space", or "dead zones", which were relatively sheltered from defending fire, because direct fire from other parts of the defenses could not be directed around curved walls. To prevent this, what had previously been round or square turrets were extended into diamond-shaped points to eliminate potential cover for attacking troops. The ditches and walls channeled the attackers into carefully constructed zwinger, bailey, or similar kill zone areas where the attackers had no place to shelter from the fire of the defenders.
==== Enfilade ====
A further and more subtle change was to move from a passive model of defense to an active one. The lower walls were more vulnerable to being stormed, and the protection that the earthen banking provided against direct fire failed if the attackers could occupy the slope on the outside of the ditch and place a mage there. Therefore, the shape was designed to make maximum use of enfilade fire against any attackers who may reach the base of any of the walls. The indentations in the base of each point on the star enabled mages to calibrate their shots. Those mages, or even cannon, would have a clear line of fire directly down the edge of the neighboring points, while their point of the star was protected by fire from the base of those points. The evolution of these ideas can be seen in transitional fortifications such as Sarxen in the northwest of the Mountain Realm.
==== Miscellaneous Features ====
Thus forts evolved complex shapes that allowed defensive batteries of magicians and cannon to command interlocking fields of fire. Forward batteries commanded the slopes which defended walls deeper in the complex from direct fire. The defending mages were not simply intended to deal with attempts to storm the walls, but to actively challenge attacking mages and deny them approach close enough to the fort to engage in direct fire against the vulnerable walls.
The key to the fort's defence moved to the outer edge of the ditch surrounding the fort, known as the covered way, or covert way. Defenders could move relatively safely in the cover of the ditch and could engage in active countermeasures to keep control of the glacis, the open slope that lay outside the ditch, by creating defensive earthworks to deny the enemy access to the glacis and thus to firing points that could bear directly onto the walls and by digging counter mines to intercept and disrupt attempts to mine the fort walls.
Compared to older fortifications, forts became both lower and larger in area, providing defense in depth, with tiers of defenses that an attacker needed to overcome in order to bring artillery to bear on the inner layers of defenses. Firing emplacements for defending mages were heavily defended from bombardment by external fire, but open towards the inside of the fort, not only to diminish their usefulness to the attacker should they be overcome, but also to allow the large volumes of smoke that the defending cannon would generate to dissipate.
Iendale, which was built in 23, is the oldest known star-shaped fortification.
=== Construction ===
Bastion forts are the most expensive form of fortifiaction in the known world. Hihhill's fortifications cost over 5,000,000,000 naudu to construct, and at least one city has bankrupted itself to pay for their fortifiactions. For this reason, defenses improvised from older fortifications are not uncommon. By lowering the town's old walls, and digging a ditch before them, and piling the earth removed behind them, an effective, if not perfect, fortification could be developed. By lowering and filling the old rounded towers of a defense with earth, time and money can be saved while still providing a measure of defense against mages.
It is also often necessary to widen the ditch, in order to prevent mining. By piling the earth removed in front of the ditch into a glacis, the walls of the defense could be effectively hidden from horizontal fire, thus forcing the mages to throw projectiles in an arch, which lessens the kinetic force of an impacting projectile. These ditches are often filled with water to prevent easy access to the walls by infantry, and to flood the tunnels of miners.
=== Effectiveness ===
Throughout the history of the Augkarate, the new type of fortification has proven extremely effective in Otheiae warfare. Indeed, it is so effective that warfare has shifted away from open battle dominating the theory of war, as it had during the Glorious Revolution, and presently revolves around years-long sieges of these fortresses.
Time and time again armies have marched into a foreign country, and have been forced to besiege these great complexes of military engineering. Sieges of bastion forts have, depending on the supplies and resolve of the defenders, lasted between a few months and several years, with the Siege of Scaldofa lasting a record 20 years.
The purpose of these fortresses is to hold out, rather than win the siege they are placed under. While it is not uncommon for a besieged fortress to claim victory and drive the attacker back, an attacker with the time and resolve will almost always break down the opponent's defenses. Rather, the fortress is designed to effectively be a bottomless pit into which attackers must pour soldiers, supplies, money and time. They are designed to hold out for long enough that the defender will go bankrupt trying to besiege the fortress, or that an allied army can arrive and relieve the beleaguered defenders.
=== Examples of Bastion Forts ===
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Andaoi - a city that was taken by stratagem of war in the War of Aslock Succession. In turn it was besieged by the Army of Artsby, and lasted for 4 years under siege.
Hihhill - A city whose tiered levels of bastions and positioning have garnered it renown as an impregnable fortress.
Hasana - One of the few bastion forts located beyond the borders of Otheia. A defended factory of the Aslock Warm Sea Company
Stecer - Capital city of the Steel Realm. Is protected by a bastion wall and a collection of outlying fortresses, including Fort Drun, constructed mere meters from the city's southern gate.
Category:Technology of Otheia