Before revision: While the Romans were focused on the siege, another Volscian force arrived from Antium (modern Anzio and NettunoPaola Brandizzi Vittucci, Antium: Anzio e Nettuno in epoca romana, Roma, Bardi, 2000 ) and attacked the Romans, and at the same time the soldiers of Corioli launched a sally.
After revision: While the Romans were focused on the siege, another Volscian force arrived from Antium and attacked the Romans, and at the same time the soldiers of Corioli launched a sally.