Low walls, deep earth and no blind spots
How the parts of a star fort fitted together against cannon fire.
Jump to: Why a star? | The parts | Earth, brick and shell | Outworks and water | Sieges
Why a star?
The bastioned system used a geometric layout of ramparts that got rid of blind spots, with the bastion replacing the medieval tower. Network of Vauban’s Major Sites: History of the bastioned fortification
A bastion is a pentagonal (five-sided) shape that points two faces towards the attacker and joins the curtain walls with two flanks. Network of Vauban’s Major Sites: History of the bastioned fortification The size and shape of bastions were worked out from how far the defenders’ guns could fire. Network of Vauban’s Major Sites: History of the bastioned fortification
This gave fortifications a star-shaped plan, with each point being a section of wall facing the attacker. Network of Vauban’s Major Sites: History of the bastioned fortification
English Heritage describes bastions as gun platforms sticking out from the wall, so defenders could fire out across the ditch or at enemies attacking the walls on either side. English Heritage: History of Berwick-upon-Tweed Castle and Ramparts
At Fort McHenry, each point of the star could be seen from the points on either side, and as few as five men could cover all the land around the fort. US National Park Service: The Star Fort (Fort McHenry)
A bastioned front is a layout where the sides protect each other. Network of Vauban’s Major Sites: glossary, Bastion
The “bastion system” is named after the diamond or angle-shaped bastions added to the fort walls. US National Park Service: Castillo de San Marcos, construction
The parts
Bastion: a low five-sided work sticking out from the main wall, made of two faces, two flanks and the gorge (the back, often left open). Network of Vauban’s Major Sites: glossary, Bastion A bastion was called “solid” when it was completely filled with earth from the rampart. Network of Vauban’s Major Sites: glossary, Bastion
Curtain wall: a straight wall between two towers or bastions. Network of Vauban’s Major Sites: glossary, Curtain wall
Ravelin (or demi-lune): a defence in front of the curtain wall, surrounded by ditches. A triangular ravelin usually had two faces meeting at a sharp angle, and often protected the gate. Network of Vauban’s Major Sites: glossary, Demi-lune or ravelin
At Tilbury, Historic England describes the ravelin as an arrowhead-shaped island in the inner moat, with guns to defend the Landport Gate. Historic England: Tilbury Fort, list entry 1021092 At Fort McHenry the NPS describes the ravelin as a triangular structure just outside the fort. US National Park Service: The Bombardment of Fort McHenry, part 1
Counterscarp: the outer sloping wall of the ditch. Network of Vauban’s Major Sites: glossary, Counterscarp
Covered way: a walkway open on the counterscarp side and protected by a parapet. Network of Vauban’s Major Sites: glossary, Covert way At Tilbury the covered way had an internal firing step, called a banquette. Historic England: Tilbury Fort, list entry 1021092
Glacis: a gently sloping bank of earth running from the top of the covered way down to the natural ground in front of the fort. Network of Vauban’s Major Sites: glossary, Glacis
Parapet: a wall of stone, wood or earth on the outer edge of a defence. On artillery forts, parapets are lower and thicker than castle battlements, with embrasures for guns. Network of Vauban’s Major Sites: glossary, Parapet Embrasure: an opening designed for a cannon. Network of Vauban’s Major Sites: glossary, Embrasure
Citadel: a fort that commanded a town, often part of the town wall, usually used as an arsenal and barracks. Network of Vauban’s Major Sites: glossary, Citadel
Earth, brick and shell
The ramparts were huge earth banks held up by walls, strong enough to take cannonballs and to carry many cannons. Network of Vauban’s Major Sites: History of the bastioned fortification
A bastioned fort’s strength came not from tall walls but from the thickness of the earth piled up behind them. Network of Vauban’s Major Sites: History of the bastioned fortification Unlike medieval high, thick walls, the bastioned system drove defences down into the ground, making them less fragile. Network of Vauban’s Major Sites: Bastioned fortifications
Fort McHenry’s walls and buildings were made of brick. US National Park Service: The Star Fort (Fort McHenry)
The Castillo is one of only two forts in the world built of coquina, a limestone made of shells; the other is Fort Matanzas. US National Park Service: Castillo de San Marcos, construction “Coquina” is Spanish for “tiny shell”. US National Park Service: Coquina, the rock that saved St Augustine
Cannonballs fired at the coquina walls burrowed in and stuck, instead of shattering the wall. US National Park Service: Castillo de San Marcos, construction
Under the Spanish the Castillo had four bastions and walls 30 feet high. US National Park Service: Castillo de San Marcos (article)
One NPS page gives the walls as 14 feet thick. US National Park Service: Castillo de San Marcos (article) Another NPS page says the walls average 12 feet (3.7 m) thick, and up to 19 feet (5.8 m) on the ocean side. US National Park Service: Coquina, the rock that saved St Augustine
Outworks and water
Vauban gradually made his forts bigger, adding outworks: ravelins and demi-lunes, then hornworks, crownworks and detached forts. Network of Vauban’s Major Sites: History of the bastioned fortification
In the plains of northern France, Vauban used water as a defence, planning to flood the land around a fortress during a siege. Network of Vauban’s Major Sites: History of the bastioned fortification
Tilbury has two deep moats, one inside the other, filled from the river. English Heritage: History of Tilbury Fort
Goryokaku covers about 125,500 square metres and is surrounded by a moat up to 30 metres wide and 5 metres deep. Visit Hokkaido: Goryokaku Fort
Tunnels run between Palmanova’s fortifications, letting soldiers move unseen by attackers. Visit Palmanova: The Fortress City
Sieges
Vauban designed a siege method in twelve separate stages. Network of Vauban’s Major Sites: Vauban
As well as fortifying towns, Vauban also captured them, and he knew no fortress was impregnable. Network of Vauban’s Major Sites: Vauban Vauban saw a fortress as a deterrent, meant to be used as little as possible. Network of Vauban’s Major Sites: Vauban
Vauban refused to write a treatise (a rule book) on fortification, because each site needed its own design. Network of Vauban’s Major Sites: History of the bastioned fortification
Vauban’s ideas were only described as “three systems” after his death; for him, fitting the land, common sense and experience were what counted. Network of Vauban’s Major Sites: History of the bastioned fortification
Neuf-Brisach is the only example of Vauban’s “third system”. Network of Vauban’s Major Sites: glossary, Third system
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