What were some of the earliest uses of paper currency and are their any interesting examples?
What did regimes like those of the French Revolution, the first french empire or the third reich put on their banknotes?
What happened with regard to currency when a regime such as those mentioned annexed new territory?
The earliest Paper Currency was developed by China. It was a result of a lack of precious metal that was needed to mint coins. As for interesting examples nothing really pops into mind but even the early Chinese notes first used in 1204 were amazingly intricate. Two hundred years later the Yaun dynasty prohibited the ownership of gold and silver coins which resulted in making all transactions in the paper currency and not coins.
That second line of questions is 'googleable'. However, the whole point of paper money was the it was backed by the government, if there was a revolution happening would you trust the government had your money?
In ancient times with Rome and the like a currencies value (with a very few exceptions) was based on its composition. Coins value is intrinsic so no matter what country the coin is from one ounce of silver is worth one ounce of silver. That's not to say that Rome for example would not re-issue coins to the area it is just that coins would circulate as metal value, intrinsic value.
In modern times of course without the backing of a metal composition currency of the conquered would be very close to worthless. In some cases very unfair exchange rates would be set to the conquerors currency or the conquered currency would just be worthless.
