Abatis,
abattis, or
abbattis is a term in field
fortificationFortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...
for an obstacle formed (in the modern era) of the branches of trees laid in a row, with the sharpened tops directed outwards, towards the enemy. The trees are usually interlaced or tied with
wireA wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
. Abatis are used alone or in combination with wire entanglements and other obstacles.
There is evidence it was used as early as the
Roman ImperialThe Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
period, and as recently as the
American Civil WarThe American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...
. Abatis is rarely seen nowadays, having been largely replaced by
wire obstacleIn the military science of fortification, wire obstacles are defensive obstacles made from barbed wire, barbed tape or concertina wire. They are designed to disrupt, delay and generally slow down an attacking enemy...
s. However, it may be used as a replacement or supplement when
barbed wireBarbed wire, also known as barb wire , is a type of fencing wire constructed with sharp edges or points arranged at intervals along the strand. It is used to construct inexpensive fences and is used atop walls surrounding secured property...
is in short supply. A form of giant abatis, using whole trees instead of branches, can be used as an improvised anti-
tankA tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
obstacle.
A classic use of an abatis was found at the Battle of the Chateauguay, 26 October, 1813, when approximately 1,300 Canadian
voltigeursThe Voltigeurs were French military skirmish units created in 1804 by Emperor Napoleon I.-Etymology:Voltigeurs hold their name from their originally conceived role of cavalry-transported skirmishers: the voltigeurs were intended to jump onto the croup of cavalry horses in order to advance more...
, under the command of Charles-Michel de Salaberry, defeated an American corps of approximately 2,300 men. Another striking example was its use by Alexander Macomb in the stunning victory at the Battle of Plattsburg.
An important weakness of abatis, in contrast to
barbed wireBarbed wire, also known as barb wire , is a type of fencing wire constructed with sharp edges or points arranged at intervals along the strand. It is used to construct inexpensive fences and is used atop walls surrounding secured property...
, is that it can be destroyed by
fireFire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
. Also, if laced together with
ropeA rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...
instead of
wireA wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
, the rope can be very quickly destroyed by such fires, after which the abatis can be quickly pulled apart by
grappling hookA grappling hook is an anchor with multiple hooks , attached to a rope; it is thrown, dropped, sunk, projected, or fastened directly by hand to where at least one hook may catch and hold. Generally, grappling hooks are used to temporarily secure one end of a rope. They may also be used to dredge...
s thrown from a safe distance.
An important advantage is that an improvised abatis can be quickly formed in forested areas. This can be done by simply cutting down a row of trees so that they fall with their tops toward the enemy. An alternative is to place explosives so as to blow the trees down.
Though rarely used by modern conventional military units, abatises are still officially maintained in
United States ArmyThe United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
and
Marine CorpsThe United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
training. Current training instructs engineers or other constructors of such obstacles to fell trees, leaving a 1 or 2 yard stump, in such a manner as the trees fall interlocked pointing at a 45-degree angle towards the direction of approach of the enemy. Furthermore, it is recommended that the trees remain connected to the stumps and the length of roadway covered be at least 80 yards. US military maps record an abatis by use of an inverted "V" with a short line extending from it to the right.
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