Tenaille
Encyclopedia
Tenaille is an advanced defensive-work, in front of the main defences of a fortress which takes its name from resemblance, real or imaginary, to the lip of a pair of pincers. It is "from French, literally: tongs, from Late Latin tenācula, pl of tenaculum".
In a letter to John Bradshaw
, President of the Council of State
in London, Oliver Cromwell writing from Dublin on 16 September 1649 described one such tenaille that played a significant part during the storming of Drogheda
.
Tenaille were a development in fortification design formalised by Vauban. To allow the defenders to access the ditches that front a curtain wall a postern
was placed low down in the curtain walls close to its centre. To protect the postern Vauban conceived the plan of establishing a work between the flanks and before the curtain, and to which he gave the name of tenaille. This work masks not only the postern, but likewise the flanks and almost the whole curtain. Suitably planned and organized, the tenaille possesses many important advantages, but in whatever manner it is designed, the tenaille will mask the fires of the flanks, and the ditches in front of it will give some cover to attackers.
The first trace that Vauban adopted for the tenaille after inventing it, was to draw it like a small front placed parallel to the curtain, and with its two small flanks parallel to those of the enceinte
. But he abandoned this plan, and substituted for it the re-entering angle formed upon the perpendicular by the lines of defence. His tenaille is eloigned 8 to 10 metres (9 to 11 yards) from the flanks and from the curtain opposite the re-entering angle.
By the end of the Napoleonic Wars
the Vaubau's design had been augmented with a straight face (un pan coupé) parallel to the curtain wall (see the middle diagram). The position of its magistral is found by laying off 24 to 25 metres (26⅔ to 28 yards) upon the perpendicular, measuring from the magistral of the curtain; and 10 metres (11 yards) to find its gorge-line
. By this plan there is formed in rear of the tenaille a kind of place of arms, of great advantage for debouch
ing into the ditch: the parapet of the tenaille was made 5 metres (16⅔ feet) thick. The profiles parallel to the flanks of the enceinte, could be rounded; and the extremities of the covering line for a length of 3 or 4 metres (10 to 13⅓ feet), could be broken inwards. The tenaille could be crossed along its centre by a great postern leading under its terra-plain; and when the ditch was filled with water, this vaulted passage served as a harbour for boats.
In a letter to John Bradshaw
John Bradshaw
John Bradshaw may refer to:* John Bradshaw , English judge* John Bradshaw , English political writer* John Bradshaw , American educator* John Bradshaw, presenter of It Is Written-See also:...
, President of the Council of State
Council of State
The Council of State is a unique governmental body in a country or subdivision thereoff, though its nature may range from the formal name for the cabinet to a non-executive advisory body surrounding a head of state. It is sometimes regarded as the equivalent of a privy council.-Modern:*Belgian...
in London, Oliver Cromwell writing from Dublin on 16 September 1649 described one such tenaille that played a significant part during the storming of Drogheda
Siege of Drogheda
The siege of Drogheda at the outset of the Cromwellian conquest of Ireland. The town of Drogheda in eastern Ireland was held by a combined English Royalist and Irish Catholic garrison when it was besieged and stormed by English Parliamentarian forces under Oliver Cromwell...
.
Tenaille were a development in fortification design formalised by Vauban. To allow the defenders to access the ditches that front a curtain wall a postern
Postern
A postern is a secondary door or gate, particularly in a fortification such as a city wall or castle curtain wall. Posterns were often located in a concealed location, allowing the occupants to come and go inconspicuously. In the event of a siege, a postern could act as a sally port, allowing...
was placed low down in the curtain walls close to its centre. To protect the postern Vauban conceived the plan of establishing a work between the flanks and before the curtain, and to which he gave the name of tenaille. This work masks not only the postern, but likewise the flanks and almost the whole curtain. Suitably planned and organized, the tenaille possesses many important advantages, but in whatever manner it is designed, the tenaille will mask the fires of the flanks, and the ditches in front of it will give some cover to attackers.
The first trace that Vauban adopted for the tenaille after inventing it, was to draw it like a small front placed parallel to the curtain, and with its two small flanks parallel to those of the enceinte
Enceinte
Enceinte , is a French term used technically in fortification for the inner ring of fortifications surrounding a town or a concentric castle....
. But he abandoned this plan, and substituted for it the re-entering angle formed upon the perpendicular by the lines of defence. His tenaille is eloigned 8 to 10 metres (9 to 11 yards) from the flanks and from the curtain opposite the re-entering angle.
By the end of the Napoleonic Wars
Napoleonic Wars
The Napoleonic Wars were a series of wars declared against Napoleon's French Empire by opposing coalitions that ran from 1803 to 1815. As a continuation of the wars sparked by the French Revolution of 1789, they revolutionised European armies and played out on an unprecedented scale, mainly due to...
the Vaubau's design had been augmented with a straight face (un pan coupé) parallel to the curtain wall (see the middle diagram). The position of its magistral is found by laying off 24 to 25 metres (26⅔ to 28 yards) upon the perpendicular, measuring from the magistral of the curtain; and 10 metres (11 yards) to find its gorge-line
Counterscarp
A scarp and a counterscarp are the inner and outer sides of a ditch used in fortifications. In permanent fortifications the scarp and counterscarp may be encased in stone...
. By this plan there is formed in rear of the tenaille a kind of place of arms, of great advantage for debouch
Debouch
Debouch is a term used in river and stream geography, and the military.-Geography:In fluvial geography, a debouch is a place where a body of water pours forth from a narrow opening...
ing into the ditch: the parapet of the tenaille was made 5 metres (16⅔ feet) thick. The profiles parallel to the flanks of the enceinte, could be rounded; and the extremities of the covering line for a length of 3 or 4 metres (10 to 13⅓ feet), could be broken inwards. The tenaille could be crossed along its centre by a great postern leading under its terra-plain; and when the ditch was filled with water, this vaulted passage served as a harbour for boats.