Demand Notes are a type of United States paper money that were issued between August 1861 and April 1862 in denominations of 5, 10, and 20 U.S. dollars. Released during the American Civil War, these notes were used to pay expenses incurred by the Union during the war. They were popularly known as "greenbacks", a name inherited by their successors, the Legal Tender and Federal Reserve Notes.
Shown here is a $5 note, dated 10 August 1861, which includes a portrait of the first Secretary of the Treasury, Alexander Hamilton, on the right, and the then-incomplete Statue of Freedom on the left. This bill is scanned from the National Numismatic Collection at the National Museum of American History.
Banknote: Bureau of Engraving and Printing (image courtesy of the National Numismatic Collection, National Museum of American History)