In
geography
Geography (from Ancient Greek ; combining 'Earth' and 'write', literally 'Earth writing') is the study of the lands, features, inhabitants, and phenomena of Earth. Geography is an all-encompassing discipline that seeks an understanding o ...
, a defile is a narrow
pass or
gorge
A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tend ...
between
mountain
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...
s or
hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as Mountain, mountains. Hills ...
s. The term originates from a military description of a route through which troops can march only in a narrow
column
A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...
or with a narrow front. On emerging from a defile (or something similar) into open country, soldiers are said to "
debouch".
Background
In a traditional military formation, soldiers march in
ranks (the depth of the formation is the number of ranks) and
files (the width of the formation is the number of files), so, if a column of soldiers approaches a narrow pass, the formation must narrow, and so the files on the outside must be ordered to the rear (or to some other position) so that the column has fewer files and more ranks. The French verb for this order is ''défiler'', from which the English verb comes, as does the physical description for a valley that forces this manoeuvre.
Defiles of military significance can also be formed by other physical features that flank a pass or path and cause it to narrow, for example impassable woods and rivers. At the
Battle of Agincourt
The Battle of Agincourt ( ; ) was an English victory in the Hundred Years' War. It took place on 25 October 1415 (Saint Crispin's Day) near Azincourt, in northern France. The unexpected victory of the vastly outnumbered English troops agains ...
, a defile formed by the woods of Agincourt and Forecourt caused a
choke point for the French army and aided the English in their victory over the French.
['' Encyclopædia Britannica Eleventh Edition''. "Agincourt". " The battle was fought in the defile formed by the wood of Agincourt and that of Tramecourt, at the northern exit of which the army under d'Albret, constable of France, had placed itself so as to bar the way to Calais against the English forces..."]
Some defiles have a permanent strategic importance and become known by that term in military literature. For example, the military historian
William Siborne names such a geographic feature in France near the frontier with Germany in his book ''Waterloo Campaign 1815'':
See also
*
*
*
*
*
*
*
*
*
*
References
{{reflist
Slope landforms