The term 'AN ARMY OF' can be completed with the solutions ARNIE (5 letters) and ANTS (4 letters). This phrase is often used to describe a large group of people or things, such as a group of soldiers or a swarm of insects. In this case, the solution ARNIE is a reference to Arnold Schwarzenegger, an actor who has starred in many action films, while ANTS refers to the small insects that often live in colonies and work together in large numbers.