A field army (or numbered army or simply army) is a military formation in many armed forces, composed of two or more corps and may be subordinate to an army group. Likewise, air armies are equivalent formation within some air forces. A field army is composed of 100,000 to 150,000 troops.
https://en.wikipedia.org/wiki/Field_armyΥποθέτω πως στις περισσότερες περιπτώσεις θα με κάλυπτε ένα απλό «στρατός», ωστόσο με ενδιαφέρει συγκεκριμένα σε αυτό εδώ το πλαίσιο:
At the outbreak of World War I, 80% of the German army was deployed as seven field armies in the west according to the plan Aufmarsch II West. However, they were then assigned to execute the retired deployment plan Aufmarsch I West, also known as the Schlieffen Plan. This would march German armies through northern Belgium and into France, in an attempt to encircle the French army and then breach the 'second defensive area' of the fortresses of Verdun and Paris and the Marne river.
https://en.wikipedia.org/wiki/World_War_I#Opening_hostilitiesΕυχαριστώ :)
