Batardeau

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Batardeau (left) at Mühlengraben / Spandau old town
A batardeau with a hemispherical spire. (Fort Lupine, France)

A batardeau (also bear , water bear , ferry ) is a dam structure in fortress construction , which is used to regulate the water level in a wet ditch.

Construction

A batardeau was designed as a brick wall that had to be strong enough to withstand the water pressure that arises when the moat is dry on one side of the batardeau and filled to the maximum on the other. For larger moats, a solid brick wall with a wall thickness of two to two and a half meters was necessary. The batardeau is only about one to one and a half meters higher than the highest expected water level, as it hinders the flanking fire of its own fortress troops. To regulate the water level, the batardeau contains a drain slide.

In order to prevent the moat from being crossed with the help of the batardeau, the top of the wall is usually pointed. There can also be bars and iron thorns. In the middle of the batardeau there is a cylindrical tower with a conical top, which is another obstacle. There are batardeau structures that can be walked on from the inside (and covered) with access to the drain slide, as well as structures in which the drain slide can only be operated from the outside via a mechanism.

Location in the fortress

The Batardeau is at right angles to the gap between two bulwarks and connects curtain wall with counterscarp . Since the enemy during a siege of the fortress by destroying the batardeau both reduces the water level in the wet trench and facilitates the passage over the trench through the ruins of the batardeau, a batardeau must be built on the most protected side of the fortress.

Web links

Model construction of the first castle gate in Lübeck, 13. – 16. Century - outer gate (left), batardeau with drawbridge, middle gate (right)
Commons : Batardeau  - collection of images, videos and audio files

Individual evidence

  1. ↑ Frederick Augustus Griffiths: The artillerist's manual, and compendium of infantry exercise JM Boddy, Woolwich 1839, p. 242.
  2. ↑ a b Hector Straith: Introductory essay to the study of fortification . London 1852, p. 14.
  3. ↑ Royal Military College, Sandhurst (Ed.): Outlines of a course of lectures on fortification, military tactics, and perspective . Spottiswoodes and Shaw, 1852, pp. 43-44