A compromise between the two has a small cadre of professional NCOs (non-commissioned officers) and officers who act as a skeleton for a much larger force. When war comes, this skeleton is filled out with conscripts or reservists (former full-time soldiers who volunteer for a small stipend to occasionally train with the cadre to keep their military skills intact), who form the wartime unit. This balances the pros and cons of each basic organization, and allows the formation of huge armies (in terms of millions of combatants), necessary in modern large scale warfare.