War debts:
Civil War: 1860: 64,842,287.88
1865: 2,680,647,869.74
Percent increase: 4,034%
Source: <a href="http://www.treasurydirect.gov/govt/reports/pd/histdebt/histdebt_histo2.htm">Debt to the Penny History 1850-1899</a>
WWII: 1940: 42,967,531,037.68...