When an army marches, it does so to the beat of drums and the call of blaring horns. These instruments are used to announce a unit's presence on the battlefield, bringing fresh hope to friends and worry to enemies. More than this, a unit's musician is crucial to keeping order when the unit attempts to change formation or should it need to rally. For trained troops, a prearranged sequence of notes can carry as much information as a bellowed order, and can do so more clearly and with greater speed.