Short answers, pulled from the story.
The Etruscans invented the ancient Roman cornu instrument for use in their funeral processions and military campaigns before Rome adopted it. These people created the original design that Roman artistic representations later copied with realistic detail.
Vegetius described the cornu as a tool used to give signals to troops during battle while trumpets sounded charges and retreats. The music of the legion included trumpets, cornets, and buccinae where the cornets regulated the motions of the colors and both instruments sounded together in time of action.
The cornu was crafted from 0.5 millimeter thick bronze sheets that overlapped at the longest sides and were fixed through soldering. Sharp tools or stones removed excess alloys while iron curved cores worked wooden pieces around 40 centimeters long to create the curved parts of each tube.
Archaeologists discovered two specimens in the ruins of Pompeii and an army signal horn in Alphen aan den Rijn in the Netherlands. Roman art also depicts the instrument among games or gladiator combat in the arena as shown clearly in the Zliten mosaic.
The cornu returned to prominence during the French Revolution as the tuba curva when François Joseph Gossec first used it in music composed for the translation of Voltaire's remains to the Panthéon on the 11th of July 1791. This revival connected ancient designs to modern state musical compositions and marked a deliberate attempt to link revolutionary ideals with classical antiquity through sound.