The Romans have by 181/180 BCE forced back the Carni to the mountains, destroyed their settlement and established a defensive settlement not far from where the Gaulish invaders had attempted to settle, on land along the Natiso south of the Julian Alps but about eight miles north of the lagoons.

The colony is to serve as a frontier fortress to protect the Veneti, faithful Roman allies, during the Illyrian Wars and act as a buttress to check the advance of other warlike people, such as the hostile Carni and Histri tribes.

Aquileia is established with Latin rights by the triumvirate of Publius Cornelius Scipio Nasica, Caius Flaminius, and Lucius Manlius Acidinus, two of whom are of consular and one of praetorian rank.

They lead three thousand pedites (infantry), mainly from Samnium, who with their families form the bulk of the settlers; they are soon supplemented by native Veneti: Aquileia's strategic military position also serves to promote the Venetic trade in amber imported from the Baltic.