French échelon, literally, rung of a ladder, from Old French eschelon, from eschele ladder, from Late Latin scala
- 1a (1) : an arrangement of a body of troops with its units each somewhat to the left or right of the one in the rear like a series of steps (2) : a formation of units or individuals resembling such an echelon <geese flying in echelon> (3) : a flight formation in which each airplane flies at a certain elevation above or below and at a certain distance behind and to the right or left of the airplane ahead
- b : any of several military units in echelon formation; also : any unit or group acting in a disciplined or organized manner <served in a combat echelon>
- 2a : one of a series of levels or grades in an organization or field of activity <involved employees at every echelon>
- b : a group of individuals at a particular level or grade in an organization <the upper echelons of the bureaucracy>
An echelon formation is a military formation in which members are arranged diagonally. Each member is stationed behind and to the right (a 'right echelon'), or behind and to the left ('left echelon'), of the member ahead. The name of the formation comes from the French word échelle, meaning ladder, which describes the staircase effect that this formation has when viewed from above or below.
Use of the formation dates back to ancient infantry and cavalry warfare when attempting to flank an enemy or to break one wing with overwhelming numbers. One of the earliest uses was at the Battle of Leuctra when the Thebans attacked the Spartan right with a column 48 men deep while their weaker center and right were refused. The echelon formation was also used by Hannibal at the Battle of Cannae, and by Frederick II of Prussia.
The tactic persists up to the present day, where it is regularly employed by all branches of the modern armed forces. Tactically, echelon formations are used because of the excellent range of vision offered to each participant in the formation. In particular, it is commonly employed by armored cavalry because of the large, overlapping fields of fire that it gives to each tank in the formation, and by combat aircraft, where the close, streamlined flight formation can allow the planes to dramatically reduce fuel consumption by "surfing" the updraft created by the wingtip vortices of the aircraft ahead.
"Echeloning" is the name of a tactic in use by the United Kingdom's Armed forces, mainly the Infantry. It consists of using a Company to attack a set of positions. Once the first platoon in the company has reached its limit of exploitation (either ammunition has been expended, fatigue has become high, or casualties are mounting) another platoon "echelons through" it, to continue onto the next position. The tactic is similar to leapfrogging.