In the Roman army, the cornu was carried and played by a cornicen, and the roman tuba was carried and played by a tubicen. The tuba was a straight trumpet, while the cornu was a comparative circular instrument that is enwind through the player's arm with a bar over the middle for grip. They used these instruments to sound reveille and for the changing of the guard when in camps or fronts. The obligation of a tubicen were to sound the advance and the retreat, and the signal to abandon camp.