An echelon formation is a military formation

Tactical formation

A tactical formation is the arrangement or deployment of moving military forces such as infantry, cavalry, AFVs, military aircraft, or naval vessels...

 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

Infantry

Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...

 and cavalry

Cavalry

Cavalry or horsemen were soldiers or warriors who fought mounted on horseback. Cavalry were historically the third oldest and the most mobile of the combat arms...

 warfare when attempting to Toquir flank an enemy or to break one wing with overwhelming numbers. One of the earliest uses was at the Battle of Leuctra

Battle of Leuctra

The Battle of Leuctra was a battle fought on July 6, 371 BC, between the Boeotians led by Thebans and the Spartans along with their allies amidst the post-Corinthian War conflict. The battle took place in the neighbourhood of Leuctra, a village in Boeotia in the territory of Thespiae...

 when the Thebans

Thebes, Greece

Thebes is a city in Greece, situated to the north of the Cithaeron range, which divides Boeotia from Attica, and on the southern edge of the Boeotian plain. It played an important role in Greek myth, as the site of the stories of Cadmus, Oedipus, Dionysus and others...

 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

Battle of Cannae

The Battle of Cannae was a major battle of the Second Punic War, which took place on August 2, 216 BC near the town of Cannae in Apulia in southeast Italy. The army of Carthage under Hannibal decisively defeated a numerically superior army of the Roman Republic under command of the consuls Lucius...

, and by Frederick II of Prussia

Frederick II of Prussia

Frederick II was a King in Prussia and a King of Prussia from the Hohenzollern dynasty. In his role as a prince-elector of the Holy Roman Empire, he was also Elector of Brandenburg. He was in personal union the sovereign prince of the Principality of Neuchâtel...

.

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

Tank

A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 in the formation, and by combat aircraft, where the close, streamlined flight formation can allow the planes to dramatically reduce fuel consumption by "surfing

Surfing

Surfing' is a surface water sport in which the surfer rides a surfboard on the crest and face of a wave which is carrying the surfer towards the shore...

" the updraft created by the wingtip vortices

Vortex

A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...

 of the aircraft ahead.

"Echeloning" is the name of a tactic in use by the United Kingdom's Armed forces, mainly the Infantry

Infantry

Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...

. It consists of using a Company

Company (military unit)

A company is a military unit, typically consisting of 80–225 soldiers and usually commanded by a Captain, Major or Commandant. Most companies are formed of three to five platoons although the exact number may vary by country, unit type, and structure...

 to attack a set of positions. Once the first platoon in the company has reached its limit of exploitation

Exploitation

This article discusses the term exploitation in the meaning of using something in an unjust or cruel manner.- As unjust benefit :In political economy, economics, and sociology, exploitation involves a persistent social relationship in which certain persons are being mistreated or unfairly used for...

 (either ammunition has been expended, fatigue has become high, or casualties are mounting) another platoon

Platoon

A platoon is a military unit typically composed of two to four sections or squads and containing 16 to 50 soldiers. Platoons are organized into a company, which typically consists of three, four or five platoons. A platoon is typically the smallest military unit led by a commissioned officer—the...

 "echelons through" it, to continue onto the next position. The tactic is similar to leapfrogging

Leapfrogging (infantry)

In infantry tactics, leapfrogging is a technique for advancing personnel and/or equipment on or past a target area being defended by an opposing force. This technique is taught in U.S. Army Basic Training and reinforced with all unit and advanced training throughout a soldier’s career...

.

Echelon formations are also commonly used by civic, or riot police to move crowds either to the left or right.

Derived meanings

The name has also been adopted by the birdwatching

Birdwatching

Birdwatching or birding is the observation of birds as a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars and telescopes, or by listening for bird sounds. Birding often involves a significant auditory component, as many bird species are...

 community to describe the familiar V-shaped formations of flights of geese

Goose

The word goose is the English name for a group of waterfowl, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....

, duck

Duck

Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...

s and other migratory birds

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, though this more symmetric formation is more strictly defined as a V formation.

In geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 an echelon formation is a set of short linear features that overlap or are staggered in a line that runs obliquely to the strike of the individual features. Echelon faults and en echelon veins

En echelon veins

In structural geology, en echelon veins are structures within rock caused by noncoaxial shear. They appear as sets of short, parallel, lenses on the surface of a rock. They are planar structures within the rock. They originate as tension fractures and are subsequently filled by precipitation of...

 are examples.

In mathematics, it refers to a kind of matrix where the non-zero elements are shaped in an echelon-like manner.

In road racing

Road racing

Road racing is a general term for most forms of motor racing held on paved, purpose-built race tracks , as opposed to oval tracks and off-road racing...

, an echelon formation is a diagonal line of racers, which allows cooperative drafting.

In sheet material response to shear stress

Shear stress

A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...

 it is typical for a series of echelon cracks to form. This is commonly seen in asphalt roads subject to shear stress imposed by aseismic fault creep

Aseismic creep

In geology, aseismic creep is measurable surface displacement along a fault in the absence of notable earthquakes.An example is along the Calaveras fault in Hollister, California. Streets crossing the fault in Hollister show significant offset and several houses sitting atop the fault are notably...

.