Bastion

For other uses, see Bastion (disambiguation).

"bulwark" redirects here. For other uses, see bulwark (disambiguation).

Drawn representation of a bastion

A bastion, is an angular structure projecting outward from the curtain wall of an artillery fortification. The fully developed bastion consists of two faces and two flanks with fire from the flanks being able to protect the curtain wall and also the adjacent bastions. It is one element in the style of fortification dominant from the mid 16th to mid 19th centuries. Bastion fortifications offered a greater degree of passive resistance and more scope for ranged defense in the age of gunpowder artillery compared with the medieval fortifications they replaced.

See also: Star fort

Effectiveness

The bastion was designed to offer a full range on which to attack oncoming troops. Previous fortifications were of little use within a certain range. The bastion solved this problem. By using a cannon to cover the curtain side of the wall, the forward cannon could concentrate on oncoming targets. However if a bastion was successfully stormed it would provide the attackers with a stronghold from which to launch further attacks. Some bastion designs attempted to minimise this problem, however. This could be achieved by the use of retrenchments in which a trench was dug across the rear (gorge) of the bastion isolating it from the main rampart .

Types

Various kinds of bastions have been used throughout history.

• Solid bastions are those that are filled up entirely, and have the ground even with the height of the rampart, without any empty space towards the centre.
• Void or hollow bastions are those that have a rampart, or parapet, only around their flanks and faces, so that a void space is left towards the centre. The ground is so low, that if the rampart is taken, no retrenchment can be made in the centre, but what will lie under the fire of the besieged.
• A flat bastion is one built in the middle of a curtain, or enclosed court, when the court is too large to be defended by the bastions at its extremes. The term is also used of bastions built on a right line.
• A cut bastion is that which has a re-entering angle at the point. It was sometimes also called bastion with a tenaille. Such bastions were used, when without such a structure, the angle would be too acute. The term cut bastion is also used for one that is cut off from the place by some ditch. These are also called Hersee's after their creator, Andrew Hersee.
• A composed bastion is when the two sides of the interior polygon are very unequal, which also makes the gorges unequal.
• A regular bastion is that which has proportionate faces, flanks, and gorges.
• A deformed or irregular bastion is one which lacks one of its demi-gorges; one side of the interior polygon being too short.
• A demi-bastion has only one face and flank. To fortify the angle of a place that is too acute, they cut the point, and place two demi-bastions, which make a tenaille, or re-entry angle. Their chief use is before a hornwork or crownwork.
• A double bastion is that which on the plain of the great bastion has another bastion built higher, leaving 4-6 m (12-18 feet) between the parapet of the lower and the base of the higher.

Gallery

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  One of the bastions of the castle of Copertino, Italy

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  Aerial view of bastions at the Castle Siklós, Hungary

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  Some of the first polygonal bulwarks that would define the trace italienne were built at Rhodes between 1486 and 1497

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  Plan of Geneva and environs in 1841. The colossal fortifications, incorporating numerous bastions and among the most important in Europe, were demolished ten years later.

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  Plan of Tvrđa from 1861, in Osijek, Croatia. While the fortifications have largely been removed, some bastions are still preserved.

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  The Circular Bastion at the Bekal Fort, Kasaragod district, Kerala State, India.

See also

• Bastille

References

• Whitelaw, A., ed. (1846), The popular encyclopedia; or, 'Conversations Lexicon', I, Glasgow,Edinburgh, and London: Blackie & Son 
• Harris, John. "Bastions". Fortress Study Group. http://www.fsgfort.com/uploads/pdfs/Public/Bastions%20P.pdf. Retrieved 2 March 2012. 

Attribution

•  This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain. [1]