sentences:  The use of the natural trumpet as a fully-fledged military signalling instrument is generally credited to the ancient Romans; a total of forty-three signals are said to have been used in the Roman army.Since the early days of the Republic, two centuriates of troops (about 160 men) were composed entirely of trumpeters; these musicians, called aenatores, employed a variety of instruments.It is now thought that the Romans adapted these instruments, and possibly also the signals sounded on them, from Etruscan models.