>Also, in ancient Rome, coinage with Caesar's face on it was traded above its bullion value. They'd kill 1/10th of your population repeatedly until you agreed to this (such was the origins of the word "decimation")

Decimation has it's origin in a military punishment for insubordination or cowardice. Where did you get the fiat currency idea from?

I learned it in latin class. It looks like I may have gotten it a bit wrong.

It's not that they killed every tenth member of whatever village they were adding to the roman empire that day, but rather than they conscripted some of them as soldiers and then killed every tenth of those who didn't obey.

I think the currency point stands though: value the money our soldiers carry, tax collectors will be along for it shortly, welcome to the Roman Empire.