A battle forged army is a term used in the Warhammer 40,000 tabletop game to describe an army that is built according to the game's official rules. These rules dictate what kinds of units can be included in an army and how many of each type can be used. For example, a Patrol detachment, which is one of the most basic types of army configurations, requires a couple of Leaders, up to three units of "troops," and two fast attack units. These rules are designed to ensure that players build balanced armies that are challenging to face in battle.