Enfilade and defilade
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For enfilade in the context of Project Xanadu, refer to Enfilade (Xanadu).
Enfilade and defilade are concepts in military tactics used to describe a military formation's exposure to enemy fire. In addition, enfilade fire is used to describe gunfire directed against an "enfiladed" formation or position. The words themselves come from French (enfiler - to skewer; défiler - to scroll).
Enfilade fire is also commonly known in English as "flanking fire".
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[edit] Enfilade
A formation or position is "in enfilade" if weapons fire can be directed along its longest axis. For instance, a trench is enfiladed if the opponent can fire down the length of the trench. A column of marching troops is enfiladed if fired on from the front or rear such that the projectiles travel the length of the column. A rank or line of advancing troops is enfiladed if fired on from the side (flank).
The benefit of enfilading an enemy formation is that, by firing along the long axis, it is relatively easier to hit individual troops within that formation. Raising or lowering the aim of the firing weapon merely directs the fire to a different point along the axis of the formation, though any pivoting movement (traverse) of the weapon is more likely to result in a miss. Enfilade fire takes advantage of the fact that aiming at a target is relatively easier than correctly estimating the range to avoid shooting too long or short. Finally, projectiles that miss an intended target are more likely to hit a different target within the formation if firing along the long axis.
Raking fire is the equivalent term in naval warfare.
[edit] Defilade
A unit or position is "in defilade" if it is protected from direct exposure to enemy fire. For an armored fighting vehicle (AFV), defilade can be synonymous with a hull-down position.
Defilade is often used to refer to a position on the reverse slope of a hill or within a depression in level or rolling terrain. Defiladed positions on hilltops are advantageous because it allows a defender to take advantage of the height of the terrain without suffering the disadvantage of being silhouetted against the sky. However, because of the slope, "dead space" that cannot be engaged with direct fire will be created in front of the position. Ideally this dead space should be covered by the interlocking fields of fire of other nearby positions, and/or by pre-planned indirect fire such as mortars or other forms of artillery.
In the case of tanks or other AFVs firing from a reverse slope, the tank will move forward only far enough that the gun when fully depressed can engage targets. This greatly reduces the size of a target that the vehicle presents, and because the hull is on a slope the effective slope of the front armor is also dramatically increased. Because of this, the degree to which a tank can depress its main gun is a significant advantage — the lower the tank can depress its gun, the less of a target the tank can present to enemy fire.
In the case of antitank weapons, and especially short-range man-portable antitank rockets, defiladed positions behind a hill have several important advantages. This is because the dead space created by the intervening crest of the hill prevents an approaching tank from using the range of its direct-fire weapons, and neither the attacker nor defender will have a clear shot until the tank is within range of the defending antitank weapon. In such engagements the tank is usually at a further disadvantage because the defender will often be camouflaged while the attacking tank will be silhouetted against the sky, giving the defender an easier shot.
In addition, if the tank fails to detect the defending antitank weapon while the tank is still defiladed, but advances beyond that position to the crest of the hill, it may expose the relatively thinner armor of its lower hull or belly to the defender. Early detection and elimination of antitank threats is an important reason that tanks attack with infantry support.
Artificial entrenchments can provide defilade by allowing troops to seek shelter behind a raised berm that increases the effective height of the ground, within an excavation that allows the troops to shelter below the surface of the ground or a combination of the two. The same principles apply to fighting positions for artillery and armored fighting vehicles as well.
[edit] References
- Russian Fortresses, 1480–1682, Osprey Publishing, ISBN 1-84176-916-9
- René Chartrand, French Fortresses in North America 1535–1763: Québec, Montréal, Louisbourg and New Orleans (Fortress 27); Osprey Publishing, March 20 2005. ISBN 9781841767147
