It looks like I get to play the Barbarians against the Romans:
https://www.boardgamegeek.com/boardgame/7843/caesar-conquest-gaul
Bibracte – 58 BC (vs the Helvetians)
The Rhein – 58 BC (vs Ariovistus’s Germanic tribes)
Bibracte was Caesar’s first major battle at the age of 42.
Here are some pictures: