In the "confidence model", some event, or series of events, such as defeats in battle, or a run on stocks of the specie that back a currency, removes the belief that the authority issuing the money will remain solvent—whether a bank or a government. Because people do not want to hold notes that may become valueless, they want to spend them in preference to holding notes that will lose value. Sellers, realizing that there is a higher risk for the currency, demand a greater and greater premium over the original value. War is one commonly cited cause of crisis of confidence, particularly losing in a war, as occurred during Napoleonic Vienna, and capital flight, sometimes because of "contagion" is another. In this view, the increase in the circulating medium is the result of the government attempting to buy time without coming to terms with the root cause of the lack of confidence itself. A crisis of confidence is particularly damaging to a fiat currency (i.e. most modern currencies), a currency whose value is unrelated to any physical quantity, as fiat money is typically backed by future tax revenues and its (typically exclusive) acceptability to the government for payment of taxes and charges.