As Marshall McLuhan, Arnold Toynbee, Peter Drucker and writers like Allan Meltzer, Anna Schwartz and Milton Friedman implicitly understood, the currency of a regime embodies the social relations of a particular social - political economy. Fixed exchange rate regimes cannot accommodate rapid change brought on by technological change or revolution. They suffer collapse.
Piera U.K. on "Currency Wars & Collapse of Empires" http://www.pieria.co.uk/articles/currency_wars_and_the_fall_of_empires