Explanation: During the Roman Empire, it became increasingly common, as the civilian institutions became weaker, for the soldiers to acclaim their own leaders as Emperor. When this happened, there was usually some amount of negotiation about particulars, but the Senate would generally acquiesce to the decision of the heavily armed military men, so long as it wasn't too egregious.

But what happened when Roman Legions disagreed with one another on which of their leaders should be Emperor?

Single-candidate elimination, vote-by-mail! First voter to get through the general's chainmail eliminates the candidate!

Ah, the wonders of civil war! I wonder why the Empire is having such a recruiting problem lately, though...