Final answer:
The Roman expansion of Latium involved Rome leading the Latin League to secure the region from hill tribes and the Etruscans, with significant steps towards territorial gains being taken after the sack by the Celts in 389 BCE. Rome offered citizenship to defeated allies to bolster its military capacity. This expansion strategy contributed to Rome's growth from a small city in central Italy to a vast empire.
Step-by-step explanation:
The Roman expansion of Latium marked the beginning of Rome's transformation from a small city-state to a powerful republic. Through its leadership in the Latin League, Rome initially united adjoining cities to push back against hill tribes and the Etruscans, who were a prior threat. The Romans built on every victory, offering defeated allies citizenship without voting rights in exchange for military support and loyalty.
After suffering a sacking by the Celts in 389 BCE, Rome rebounded and intensified its expansion efforts. A decisive moment came in 338 BCE, when after beating the Latin League, instead of imposing punishment, Rome extended an offer of citizenship to these cities, enhancing Rome's manpower with each conquest. The elites of these cities saw the advantage of collaborating with Rome, benefiting from the shared spoils of victory and having a stake in politics as long as loyalty was maintained.
Located on the easily defensible hills of the Tiber River, Rome capitalized on its advantages to expand its territory, incorporating strategic administrative methods and border defenses, like the employment of dromedary camels, to secure its frontiers. Eventually, the Roman Republic spread its domain across the Mediterranean, shaping the political and cultural landscape of western Europe. However, despite its vast expansion, the empire eventually encountered decline in the third century CE.