The Daily Beat:
Drummers communicated orders to the troops in battle and in camp. Drums signaled the routines of the day, from reveille -- beat at sunrise -- to tattoo -- beat as a signal for lights out. "As there is a necessity for the Army to rise and turn out every morning at Reville-beating [sic] -- they ought to go to rest early," ordered George Washington. "All lights must be out at 9 o'clock in the evening, and every man to his tent."