Cottius, king of the Cottii, was a prudent and far-sighted ruler. After Caesar’s assassination in 44 B.C., Rome plunged into a bloody civil war. Hence, several Gallic peoples in the Alpine regions seized the opportunity to rebel. The Salassi, in particular, repeatedly entrenched themselves in the mountain passes in the hope of escaping Roman rule. Their uprisings, however, were finally crushed with the conquest of their territory and the foundation of Augusta Praetoria. Cottius, by contrast, recognised that, despite Rome’s internal conflicts, it remained far too powerful an adversary to challenge openly. Indeed, during the reign of his father, Donnus, the Cottii, a Celtic-Ligurian people settled in the Susa Valley, had already chosen the path of cooperation. In 61 BC they had made an agreement, guaranteeing Caesar’s legions safe passage along the route to the Montgenèvre Pass.
That alliance brought the Cottii decades of peace and prosperity. Cottius therefore saw no reason to repudiate the treaty his father had concluded. On the contrary, once Augustus had consolidated his power, the king of the Cottii worked to strengthen the long-standing friendship with Rome. In 13 BC he renewed the alliance (foedus) and, to commemorate the occasion, commissioned the construction in Segusium, the capital of his kingdom, modern-day Susa, of a monumental arch dedicated to the emperor. Cottius inaugurated the monument between 9 and 8 BC.
A monument celebrating an alliance: the Arch of Augustus of the Roman Susa
The Arch of Augustus at Susa was built using locally quarried limestone and marble by Italic craftsmen, some of whom came from Rome. The monument consists of a single archway covered by a barrel vault. The arch is framed by pilasters with Corinthian capitals, a decorative motif echoed by the four freestanding columns positioned at the outer corners of the structure. Above these are the entablature, embellished with a sculpted frieze, and the attic, which bears the dedicatory inscription.
“Imp(eratori) Caesari Augusto, Divi f(ilio), pontifici maxumo, tribunic(ia) potestate XV, imp(eratori) XIII; M(arcus) Iulius, regis Donni f(ilius), Cottius, praefectus ceivitatium quae subscriptae sunt: Segoviorum, Segusinorum, Belacorum, Caturigum, Medullorum, Tebaviorum, Adanatium, Savincatium, Egdiniorum, Veaminiorum, Venisamorum, Iemeriorum, Vesubianorum, Quariatium et ceivitates quae sub eo praefecto fuerunt”1.
The frieze consists of four bas-reliefs depicting the ceremonies associated with the alliance between Cottius and Augustus. The scenes represent, in sequence: the sacrifice of animals for purification (the suovetaurilia); a rite dedicated to the Dioscuri; the representatives of the fourteen peoples that made up the kingdom of Cottius; and finally, a fourth scene that is now, unfortunately, illegible due to the deterioration of the monument2. The Arch of Susa is exceptional among Roman honorary monuments. It is one of the few surviving arches erected to commemorate a political alliance rather than a Roman military victory. Cottius commissioned its construction on a site regarded as sacred, as evidenced by the presence, in the immediate vicinity, of a Celtic cup-marked altar.
The Roman rule
After Cottius, the kings of his dynasty continued to rule Susa for a further two generations. However, his grandson Cottius II died without leaving any heirs, and following his death Rome assumed direct control of the territory. The town consequently became an important settlement controlling the route leading into Gaul. The Romans embellished Susa with significant public buildings, including an amphitheatre, constructed in the second century AD, and the town forum with its raised temple, the remains of which lie beneath present-day Piazza Savoia.
In the 3rd century, the settlement was incorporated within the city walls still visible. These include the characteristic entrance gates: Porta Savoia, Porta di Francia and Porta di Piemonte.
The triangular layout was designed to improve the city’s defensive capabilities.
Samuele Corrente Naso
