Star shaped forts are a type of fortification that remained popular from the mid-15th century right up until the end of the 19th and they evolved for two main reasons.
First, they aimed to counteract the game-changing effects of gunpowder during sieges, with traditional square and ring-shaped forts now easily breached by cannon fire. Second, star forts also mitigated a key defensive weakness traditional forts had become increasingly vulnerable to – ‘sapping’, or mining under the walls, by foes out of the firing line.
Star forts countered – to a degree-the effects of cannon fire by removing most perpendicular targets for the attacking force. The design was chosen as cannon balls made short work of square-on fortifications largely due to their extensive surface area and lack of absorptive support when a shot made contact. This was because medieval castle and fort walls, which accounted for a large proportion of existing strongholds, had been designed to be relatively thin but high, making it hard for enemies to scale them and difficult for siege engines to fire over.
The advent of cannon fire, however, allowed these walls to be hit directly and with a ferocity that would easily demolish the stone and clay.
As such, this new form of fortification was built out of a series of interlocking and/or separate triangular bastions, which encircled the central town or keep within.
The bastions were much thicker than standard walls and much flatter too, meaning that any cannon shot hitting them straight on would have its kinetic energy spread out and absorbed by successive layers of masonry. Further, any shot that was not a direct hit, or completely perpendicular, would glance off with little damaging effect.
The second reason why the star-shaped fort became widely adopted was that while it limited effective angles of attack for the offensive enemy force, it maximized those of the defensive one. This was due, simply, to the geometry of their bastions. By creating a series of triangular spits that could be manned by gunners, attacking forces could be engaged over a far greater angle – over 180 degrees – and, more importantly, those forces that did reach the walls, could be continuously fired on from the side and rear. These advantages were generally not granted by existing strongholds, as their flat-on walls meant infantry could only fire in a small arc in one direction – ie perpendicular to the wall. If forces did manage to reach the base, they could not be effectively engaged either as shooting straight down is very awkward.
Despite originating in the mid-15th century in Italy, by the 18th century star forts were a common sight in France, Germany, Croatia, Hungary and many other western nations (later spreading as far east as Japan). Many are acclaimed in historical record as key turning points in major battles. Indeed, the reign of the star fort only came to an end with the arrival of explosive shells towards the latter end of the 19th century.
Top 3 fortifications
The motte-and-bailey was a castle built on top of a natural or man-made mound. The walls and keep were usually made of stone.
2. Older – Hill fort
One of the earliest defensive man-made structures, hill forts were large earthworks consisting of a series of earthen walls and ditches built around a small settlement.
3. Oldest – Citadel
A citadel was a structure attached to a large town or city, either within its outer walls or part of them. Citadels provided a base for the city’s soldiers.