Recruitment is not so simple. When recruiting a unit, you can select the army you want it in, and recruit it. However, it will not give you an entire unit, only a small band of men, which will replenish to a full unit over time. You can improve this by building granaries, souterrains, and arenas, all of which have replenishment multipliers. This changes the focus of unit construction, to unit replenishment and preservation, placing a much greater value on each unit, than in previous Total War games. It also prevents being able to recruit a huge army within one turn without a substantial amount of money.