The battle at Alesia was a turning point in the Roman conquest of Gaul. Julius Caesar built an enormous fortification around the Gallic town of Alesia, and then successfully fought off both an attack from the outside and a sally by the defenders within the fortifications, effectively ending the Gallic Wars and establishing Roman dominance over Gaul.
The fortress at Alesia contained multiple camps and fortresses, and had a circumference of over 14 miles. The Roman army, prepared to be besieged, erected two separate walls in facing opposite directions, effectively starving out and frustrating the relief army for the Celtic defenders.
Before even reaching the actual Roman fortification, ancient warriors had to run through a gauntlet of traps like water-filled trenches, sharpened stakes, and prongs arranged like a giant hedge of knife thorns.
Roman historian Julius Caesar's attempt to colonize and conquer enemy forces at Alesia had to overcome difficult terrain and defend against an army of 35,000 Gallic warriors. Despite these obstacles, Caesar and his army had the upper hand due to their fortifications, artillery, and the strength and organization of his troops.
Caesar gives a long speech, written to demonstrate the extremities that people will go to during war. The people of Alesia, an entire pan-tribal group, are trapped inside a hillfort without the knowledge of any news or reinforcement, running low on food and having a hardcore debate amongst themselves, with some considering to resort to cannibalism as a last resort.