AN ARMY

An army (from Latin Armata "act of arming" via Old French armée), in the broadest sense, is the land-based armed forces of a nation. It may also include other branches of the military such as an air force. Within a national military force, the word Army may also mean a field army, which is an operational formation, usually made up of one or more corps.

In several countries the army is officially called the land army to differentiate it from an air force called the air army, notably France. In such countries, the word "army" on its own retains its connotation of a land force in common usage. The current largest army in the world by number of active troops is the People's Liberation Army of China with 2,250,000 active troops and 800,000 reserve personnel.

A standing army is an army composed of full-time career soldiers who 'stand over', in other words, who do not disband during times of peace. They differ from army reserves who are activated only during such times as war or natural disasters.

By definition, irregular military is understood in contrast to regular armies which grew slowly from personal bodyguards or elite militia

The Roman army was the world's first professional army. It had its origins in the citizen army of the Republic, which was staffed by citizens serving mandatory duty for Rome. The reforms of Marius around 100 BC turned the army into a professional structure, still largely filled by citizens, but citizens who served continuously for 25 years before being discharged.

The Romans were also noted for making use of auxiliary troops, non-Romans who served with the legions and filled roles that the traditional Roman military could not fill effectively, such as light skirmish troops and heavy cavalry. Later in the Empire, these auxiliary troops, along with foreign mercenaries, became the core of the Roman military. By the late Empire, tribes such as the Visigoths were bribed to serve as mercenaries.

Armies as armed services

Western armies are usually subdivided as follows:

* Corps: A Corps usually consists of two or more Divisions and is commanded by a Lieutenant General.
* Division: Each division is commanded by a Major General, and usually holds three Brigades including infantry, artillery, engineers and communications units in addition to logistics (supply and service) support to sustain independent action. Except for the Divisions operating in the mountains, all the Divisions have at least one armored unit, some have even more depending upon their functionality. The basic building block of all ground force combat formations is the infantry division. A typical division would hold three infantry brigades.
* Brigade: A Brigade is under the command of a Brigadier General and comprises three or more Battalions of different units depending on its functionality. An independent brigade would be one that primarily consists of an artillery unit, an infantry unit, an armor unit and logistics to support its actions. Such a brigade is not part of any division and is under direct command of a corps.
* Battalion: Each battalion is commanded by a Lieutenant Colonel who commands roughly 600 to 900 soldiers. This number varies depending on the functionality of the battalion. A battalion comprises either three batteries or four companies - and other arms excluding armoured units that are organised into squadrons each under the command of a major and comprising of individual subunits called sections (which are further divisible into platoons and squads).