You forgot (c), wars financed with borrowed money. These have happened in conditions regardless of currency configuration (fiat, pegged, silver, gold, bimetallic, whatever).
True, but nobody will loan money to a country that is not fiscally responsible (i.e., able to pay it back). A country that must be fiscally responsible to finance its wars will not semi-permanently invade multiple foreign countries.
The US gets out of this by being able to do quantitative easing.
