Quote Originally Posted by MeinPanzer
Polybius (4.19.4) tells us that the Cretans and the Lacedaimonians utilized the flute in combat in place of the horn, so it seems this may only have been a characteristic of Doric Greeks during the EB timeframe.

But the horn would be used to sound the charge or the retreat. The fife was used to give the soldiers the marching rythm, and the "pushing" rythm (for the hoplites that is).