During the colonization of Gaul, his legions came under siege by the Boii, who surrounded their encampment. Tiberius ordered his troops to hold, anticipating reinforcements, but the Boii attacked after three days of waiting. The exits of the fort were so packed with enemy soldiers that the Romans were unable to get out, and by the time they fought their way to open ground, Gauls had broken through the defenses in two other places. As many as 5,000 Romans were killed before the Boii were finally repelled.
Tiberius settled in Placentia at the end of his consulship, and little is written about him after that time. When an army of Ligurians menaced the city in 193 BC, Tiberius sent a dispatch to Rome requesting troops, and an army of veterans who had served under him against the Boii was raised and sent to Gaul in his defense.