Final answer:
Caesar's last meeting with the Gauls was at Alesia in 52 BCE, marking the end of the Gallic Wars with significant casualties.
Step-by-step explanation:
The last time Julius Caesar met with the Gauls was at Alesia. This significant engagement took place in 52 BCE when Caesar besieged Alesia, an important town for the Gauls. The conflict resulted in substantial casualties, including the deaths of women and children. Caesar's campaigns in Gaul led to the deaths and enslavement of a staggering number of people - in some accounts, as many as one million Gauls were killed during Caesar's conquest. Alesia marked the culmination of Caesar's Gallic Wars and demonstrated his military prowess.