The people of Rome threw a party in 46 B.C. that would be remembered for many years to come. Julius Caesar had just returned, having crushed the followers of his great rival, Pompey the Great. Writing nearly two centuries later, the Roman historian Dio Cassius describes how in the first few days of his triumph the recently proclaimed dictator “proceeded homeward with practically the entire populace escorting him, while many elephants carried torches.”

In addition to the excitement caused by the exhibition of a giraffe—dubbed a “camleopard” because it resembled a cross between a camel and leopard—Romans witnessed the preparations for another astonishing spectacle that would be the culmination of the festivities: a naval battle on a man-made lake built in the Campus Martius filled with water from the nearby Tiber River.

There, two fleets of biremes, triremes, and quadriremes with 4,000 galley slaves and 2,000 crew members on board clashed in a full-scale reconstruction of a naval battle. Roman historian Suetonius, writing in the first century A.D., recorded that people from all over Italy attended. Stalls were set up nearby and the streets filled with sex workers, thieves, and vendors. So many people tried to go that some slept in the street the night before to secure good seats. People even died in the crush of the crowds, including two senators. The astonishing spectacle known as the naumachia—from the Greek word for naval battle—had been born.

Actors Aweigh!

The naumachia joined the ranks of existing Roman spectacles and entertainment, such as the gladiator fight (munus) and exotic animal hunt (venatio). These events attracted thousands of spectators from all social classes. Not only did they serve to amuse the public, they also served as a demonstration of power, of Rome’s preeminence in engineering, and the strength of its civilization.

During his time, Caesar’s naumachia was probably the most complex event held in ancient Rome. The naval battle was not merely a free-for-all, but a carefully staged portrayal of a historic battle between the fleets of Tyre and Egypt, two of Rome’s traditional enemies. Later naumachiae would reimagine historic battles between Athens and Persia, or Rhodes and Sicily.

View Images A relief of a trireme, a vessel powered by three banks of oars, depicts the kind of boat often preferred for Roman naumachia. DEA/ALBUM

For all its theater, these events were not simulations. They were real battles, in which violence, mutilation, blood, and drowning made them as macabre a spectacle as a gladiator fight. To man the ships, the participants—known as naumachiarii—wore the uniforms of the two sides. They were typically prisoners of war or convicts who had been sentenced to death, though free men could take part, too. In fact, it is recorded that a praetor—a high-ranking official—participated in Caesar’s naumachia.

The extensive planning required to stage the event explains why only around a dozen more were held after Caesar’s. A naumachia was massively expensive. Planners needed not only a colossal budget but also an appropriate site. They needed a crew of skilled craftsmen and engineers to create the theater, the seating, and the ships. They also needed a team to choreograph the action, and a sufficient number of participants to bring it to life.

Some naumachiae were staged on natural bodies of water. In 40 B.C. one was organized in the Strait of Messina (between Sicily and Italy), on the orders of Sextus, Pompey’s younger son and enemy of Octavian (later Emperor Augustus). On this occasion, Sextus chose to re-create a recent battle: his own naval victory over Octavian. Sextus’s performance was even held in full view of his defeated rival as a calculated gesture of contempt.

A century or so later Emperor Claudius staged his own mock sea battle—a portrayal of a historic battle between Sicily and Rhodes—on Fucine Lake in central Italy. One hundred boats and as many as 19,000 combatants (all convicts) took part in the extravaganza according to the historian Tacitus. To force them to fight, armed guards were stationed on pontoons around the lake. Tacitus recounts that although the battle was “one of criminals, it was contested with the spirit and courage of free men; and, after much blood had flowed, the combatants were exempted from destruction.”

Man-made Maritime Marvels

Natural bodies of water might have been less expensive to use, but they were not as conducive to watching. And since watching was the fundamental purpose of these events, other theaters had to be created. The sight of a huge, specially dug lake, equipped with stands for spectators, would become an important part of the performance itself.

Julius Caesar’s pioneering naumachia in the Campus Martius was held in a large, artificial lake that was filled in immediately after the battle had ended, probably to prevent the risk of disease from stagnant water. In 2 B.C. Augustus created an artificial lake of his own on the right bank of the Tiber River to hold a naumachia to celebrate the inauguration of the Temple of Mars Ultor in the Forum of Augustus. The Naumachia Augusti—the term “naumachia” was by then used to describe the body of water itself as well as the spectacle staged there—became regularly used for such events in Rome, at least until the end of the first century A.D.

Rather than excavating a lake, other emperors would flood amphitheaters with water. The first such recorded venue was pioneered during the reign of Nero, who organized a water battle in a stone and wood amphitheater he had built in the Campus Martius in A.D. 57. A few years later, Nero organized another naval show in the same amphitheater. Historians recorded great admiration at the amazing speed with which the site was not only filled, but also emptied in order to allow a wild animal hunt and gladiator games to take place on the same day. A few months later the structure burned to the ground during the Great Fire of Rome.

View Images It is believed the last mock naval battle of the Roman era was held in A.D. 248 to celebrate the millennium of Rome’s founding. It was ordered by Emperor Marcus Julius Philippus (Philip the Arabian), depicted on this golden aureus. BRIDGEMAN/ACI

Perhaps ancient Rome’s most iconic building, the Colosseum was purported to be the site of several naumachiae. In A.D. 80, as part of its dedication, historians report that Emperor Titus decided to hold two naumachiae: one on an artificial lake created by Augustus and the other in the Colosseum itself. During its first year, it was possible to flood the Colosseum with enough water for ships to sail (the tunnels and storage rooms under the floor, the hypogeum, were built later, during the reign of Domitian). Constructed on the space left by the artificial lake beside the Domus Aurea (the Golden House, formerly Nero’s Palace), the low-lying Colosseum could be flooded and drained with relative ease, using a series of canals and pools.

Sources mention later naumachiae, such as the one held by Trajan to celebrate his conquest of Dacia (modern-day Romania), a territory with an abundance of mineral deposits that enriched the Roman Empire at the height of its expansion. Trajan’s event took place in a pool near Vatican Hill, the remains of which were located in 18th-century excavations near the fortress of Sant’Angelo. Another major mock battle in Rome is recorded in A.D. 248, when Emperor Marcus Julius Philippus (sometimes known as Philip the Arabian due to his Syrian heritage) celebrated the thousandth anniversary of Rome’s founding with a naumachia.

These giant spectacles quickly fell out of favor after Philip’s naumachia, the last recorded event of its kind in the Roman era. Perhaps the empire’s increasing weakness and financial troubles in the third century led to the decline in popularity.

Imitating History

Fascination with the naumachia’s combination of cruelty and frivolity survived. Centuries later, they were still remembered as a colorful and intriguing example of the megalomania of the emperors and the Roman love of public spectacles. When interest in antiquity was renewed in the Renaissance, naumachiae were revived as well, albeit in a notably toned-down form. In the mid-17th century, as Spain’s ungainly empire tipped into decline, another imperial Philip—King Philip IV—amused himself watching a flotilla perform pretend military maneuvers on the lake in the Buen Retiro palace in Madrid. An elaborate river-based naumachia was also held in the Spanish city of Valencia in 1755, to celebrate the canonization of a local saint.