Oath of the Horatii (1784)
Jacques-Louis David, Public domain, via Wikimedia Commons

According to legend, Rome was founded on April 21, 753 BC by the twin brothers Romulus and Remus, descendants of the legendary Trojan hero Aeneas. After killing his brother Remus, Romulus became the first king of Rome. In any case, Rome began along the Tiber River as one of the many small city-states dotting the coastal regions of the Mediterranean Sea.

Starting with Romulus, seven legendary kings ruled the city of Rome, gradually expanding it from an unimportant tradepost populated by unsavory people into a regional power famous for its disciplined military.

Like the Egyptians and other ancient peoples, the Romans used instruments such as the cornua (horn) and tuba (trumpet, literally "tube") to coordinate troop movements during battle. Other than this, however, the Romans tended to fight in silence, allowing orders to be heard clearly and projecting an unnerving sense of discipline to their opponents. A certain tone of amused condescension can be heard as the Romans wrote about the use of music among their enemies.

...the Parthians do not encourage themselves to war with cornets and trumpets, but with a kind of kettledrum, which they strike all at once in various quarters. With these they make a dead, hollow noise, like the bellowing of beasts, mixed with sounds resembling thunder, having, it would seem, very correctly observed that of all our senses, hearing most confounds and disorders us, and that the feelings excited through it most quickly disturb and most entirely overpower the understanding.

Indeed, I have observed that even the Barbarians across the Rhine sing savage songs composed in language not unlike the croaking of harsh-voiced birds, and that they delight in such songs. For I think it is always the case that inferior musicians, though they annoy their audiences, give very great pleasure to themselves."

The Roman Kingdom lasted for nearly two and a half centuries, until the reign of the seventh king, Lucius Tarquinius Superbus. This king was an overbearing tyrant who aliented the Senate and the people of Rome and was finally overthrown after his son, Sextus Tarquinius, forced himself on a Roman noblewoman named Lucretia. Rather than live with the shame, Lucretia publicly took her own life. Upon learning this, Lucretia's husband, Lucius Tarquinius Collatinus (who was the king's second cousin) and another Roman named Lucius Junius Brutus swore an oath:

By this blood, most pure before the outrage wrought by the king's son, I swear,
and you, O gods, I call to witness that I will drive hence Lucius Tarquinius Superbus,
together with his cursed wife and his whole blood, with fire and sword and every means in my power,
and I will not suffer them or anyone else to reign in Rome.

Tarquinius Superbus and his family were driven out, and the Romans declared they would never again be ruled by a king.