 He proved an astute commander, defeating Caesar at the Battle of Gergovia, but Caesar's elaborate siege-works at the Battle of Alesia finally forced his surrender.Despite scattered outbreaks of warfare the following year, Gaul was effectively conquered.Plutarch claimed that during the Gallic Wars the army had fought against three million men (of whom one million died, and another million were enslaved), subjugated 300 tribes, and destroyed 800 cities.