Enfilade and defilade

This article is about the military concepts. For the computer science term, see Enfilade (Xanadu). For the architectural term, see Enfilade (architecture).

Diagram showing enfilade firing: the cannons at top are firing on a rank of soldiers from a flanking position

Enfilade and defilade are concepts in military tactics used to describe a military formation's exposure to enemy fire. A formation or position is "in enfilade" if weapons fire can be directed along its longest axis. A unit or position is "in defilade" if it uses natural or artificial obstacles to shield or conceal itself from enfilade.^[1] The words come from French enfiler ("to put on a string or sling") and défiler ("to slip away or off").

Enfilade fire, a gunfire directed against an enfiladed formation or position, is also commonly known as "flanking fire".^[1] Raking fire is the equivalent term in naval warfare. Strafing, firing on targets from a flying platform, is often done with enfilade fire.

Enfilade

Top to bottom: a German bunker on Juno Beach with wounded Canadian soldiers, 6 June 1944. The same bunker in September, 2006. Finally, the view of bunker's enfilading field of fire with respect to the seawall

A formation or position is "in enfilade" if weapons fire can be directed along its longest axis.^[2] 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 (from the flank).^[1]

The original concept of enfilade fire is one for field artillery,^{[citation needed]} where battery officers strive to place their weapons on an enemy's flank, firing down his battle or trench line and achieving greater effectiveness. Napoleon was a master at this, as was artilery fire at the battle of Second Manassas. When naval formations "Cross the T" (see below), they have achieved the superior battle position of firing on the enemy along his long axis. The benefit of enfilading an enemy formation is that, by firing along the long axis, it becomes easier to hit targets within that formation. Enfilade fire takes advantage of the fact that it is usually easier to aim laterally (traversing the weapon) than to correctly estimate the range to avoid shooting too long or short. Additionally, both indirect and direct fire projectiles that might miss an intended target are more likely to hit another valuable target within the formation if firing along the long axis.

Defilade

A unit or position is "in defilade" if it uses natural or artificial obstacles to shield or conceal. For an armored fighting vehicle (AFV), defilade is synonymous with a hull-down or turret-down position.

Defilade is also 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 "dead space" – a 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 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.

The enfilade-defilade combination

Unit sited in defilade threatens an enemy that decides to pass it and move forward, because they would be put in an enfiladed position when moving in a rank.^[1] The friendly unit would be in a position that is shielded by terrain from direct enemy fire, while still being able to fire on the enemy in an effective manner.

See also

• Raking fire
• Crossing the T
• Reverse slope defence
• Plunging fire

References

1. ^ ^{a b c d} Chris Bellamy (1990). The Evolution of Modern Land Warfare: Theory and Practice. Routledge. ISBN 0415020735. http://books.google.com/books?id=AAQ-AAAAIAAJ&lpg=PA24&dq=Enfilade%20defilade&pg=PA24#v=onepage&q=Enfilade%20defilade&f=false. 
2. ^ Corps, United States Marine (2007-03-01). Marine Rifle Squad. pp. 2.10. ISBN 9781602060630. http://books.google.com/books?id=nOVGjqUavScC&lpg=SA2-PA10&dq=%22plunging%20fire%22&pg=SA2-PA10#v=onepage&q&f=false. 

Further reading

• 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