In republican Rome, founding a new colony was a complex political act that followed a detailed political and religious script. In Rome itself, this included a senatorial decree, the passing of a law by a legislative assembly, the election of colonial commissioners, the enlistment of the colonists, and the official departure to the settlement location (deductio). On site, the officials would take the auspices, demarcate the urban core of the new settlement with a special plow with a bronze plowshare by plowing the so-called sulcus primigenius (‘primeval furrow’) around the site of the new city, and purify the colonists in a ritual called lustrum, thereby also constituting them as a new civic community grounded in the new urban settlement.
Respect for ritual protocols and political procedures was deeply engrained in Rome’s cultural imaginary, and every magistrate was well advised to abide as far as possible and/or convenient by the system of rules that governed public affairs, simply to avoid trouble down the road. And thus, when Antony had the idea of re-establishing a colony at Capua to settle veterans, a territory that Caesar had used for the same purpose, he seems to have checked with Cicero, as an expert in augural law and a consular, whether the plan would run into religious objections. Cicero’s reply was that, from the point of view of religious law, it was not permitted to found another colony in the territory of an already existing one; what was feasible was to add new settlers to the colony already in place. This was probably not quite the response Antony was hoping for, but he seems to have accepted Cicero’s ruling — for Capua. But when his mind turned to another location in the vicinity — Casilinum — , which had also been used for a colonial settlement by Caesar, he decided to dispense with consultation and simply went ahead, founding (it seems) an entirely new colony in the territory of the old one, essentially ignoring Cicero’s ruling on Capua (which, so Cicero argues, of course applied to Casilinum, as to any other location, as well).