The expansion was driven by a combination of strategic necessity, economic interests, military ambition, and the Roman Republic's political structure, which incentivized conquest through personal and national prestige, especially as Rome began to recover from the sacking of Rome. This event is often referred to as the Gallic Sack of Rome, during which the Senones, led by their chieftain Brennus, invaded the Peninsula and laid siege to Rome. The event marked a significant moment in Roman history, and while it did not result in long-term Gaulish dominance over Rome, it left an indelible mark on the Roman psyche, which would influence their later military strategies.