Greenback

 A legal tender  popularly called a greenback was created in 1962 due to the Civil War. It was unsecured by coin but on a par with notes that were backed by coin.

In 1866 Sec. of State McCulloch began retiring them. This created lots of controversy with discussions and laws to condemn and support it.

It was finally decided in 1879 that the greenback could be redeemed for gold. A reserve of 100 million was set aside for this but confidence was so great in the government that few were presented for surrender. It remained a premanent part of the nation's currency.