TENABLE, (Tenable, Fr.) Such as may be maintained against opposition; such as may be held against attacks.
TENAILLE, Fr. (This word literally means shears.) A military evolution which was performed in the times of the ancients.
A phalanx, attacked by a lozenge or triangular wedge, bent its right and left forward by a half-quarter wheel each wing on their common centre; and when they found themselves opposite the sides of the enemy’s arrangement, they each marched on their own side, perpendicular to their line; by which means they both inclosed and attacked the enemy together, at the same time, while the head was engaged and at blows with the centre of the phalanx that had kept its ground. Such is the description authors have left us of the design and effects of this manœuvre.
The tenaille had considerable advantage over the triangular wedge; but, according to Chevalier Folard, it was not equally efficacious against the column. The latter could alter the direction of its march, and fall upon one of the wings, whether in motion or not, or detach the section of the tail or rear to take its wings in flank, while it was occupied in making the quarter conversion. The column and tenaille were formed for acting against each other, and could only be victorious over one another by the superior abilities of their commander. However, the column was always exposed to less danger than the tenaille, for the latter could not pursue the column without changing its order; whereas the column must destroy, and in a manner annihilate the tenaille, in case it should once break it.
The tenaille is unquestionably an excellent manœuvre, and strictly conformable to a very wise maxim, which directs us to multiply our strength and efforts as much as possible against one point. It is sometimes made use of in war without being sensible of its advantages; turning a flank with a longer line, is in fact the tenaille. This, however, does not hinder the manœuvre from being well performed; for the nature of ground not being level like a sheet of paper, the commander in ranging his troops, according to the advantages of the situation, does not form a perfect tenaille, such as may be drawn or sketched out, but one of an irregular kind, which produces the same effects; and this is what should be sought on all occasions. This order is also called a potence.
Tenailles, in fortification, are low works made in the ditch before the curtains. There are three sorts: viz. the first are the faces of the bastions produced till they meet, but much lower; the second have faces, flanks, and a curtain; and the third have only faces and flanks.
Single Tenaille, (Tenaille simple, Fr.) is a work whose front is advanced towards the country, having two faces, forming a re-entering angle: its two long sides terminate on the counterscarp, opposite to the angle of the shoulder.
Double Tenaille (Tenaille double, ou flanquée, Fr.) is a work whose front, having 4 faces, forms 2 re-entering, and 3 salient angles: its long sides are likewise parallel, and terminate on the counterscarp, opposite to the angle of the shoulder. Both the single and double tenailles have this fault, viz. that they are not flanked or defended at the re-entering angle, because the height of the parapet hinders the soldiers from discovering before that angle. Therefore tenailles should only be made when there is not room enough to make horn-works. The ramparts, parapets, ditches, covert-way, and glacis of tenailles, are the same with other out-works.
Tenaille of a place, is what is comprehended between the points of two neighboring bastions; as the faces, flanks, and curtains. Hence it is said, the enemy attacked the whole tenaille of a place, when they made two attacks on the faces of the two bastions.
Tenailles, Fr. Pincers, nippers, sheers, tenails.