How was the government system in Gaul?

[Gobae]

Vercingetorix could probably be more closely equated to General Eisenhower in WW2 when he was appointed "Supreme Commander of Allied forces in Europe". Vercingetorix oversaw and lead a confederation of Clans as "war leader" but didn't have the authority to rule them as a king would.

The main difference in my analogy is that Vercingetorix was also Chieftain of his clan while Eisenhower didn't (at that time) hold a political position. In fact that was probably the biggest issue delaying Vercingetorix's acceptance; the other clans had to balance accepting him as "war leader" while making sure they would retain the leadership of their chosen Chieftains.