A field army (or numbered army or simply army) is a military formation in many armed forces, composed of two or more corps. It may be subordinate to an army group. Air armies are the equivalent formations in air forces, and fleets in navies. A field army is composed of 80,000 to 300,000 soldiers. History Specific field armies are usually named or numbered to distinguish them from "army" in the sense of an entire national land military force. In English, the typical orthographic style for writing out the names field armies is word numbers, such as "First Army"; whereas corps are usually distinguished by Roman numerals (e.g. I Corps) and subordinate formations with ordinal numbers (e.g. 1st Division). A field army may be given a geographical name in addition to or as an alternative to a numerical name, such as the British Army of the Rhine, Army of the Potomac, Army of the Niemen or Aegean Army (also known as the Fourth Army). The Roman army was among the first to feature a formal field army, in the sense of a very large, combined arms formation, namely the sacer comitatus, which may be translated literally...