In 1860, as Abraham Lincoln was elected president, 11 slaveholding southern states seceded from the US union, forming the 'Confederate States of America'(CSA) which led to a civil war.

In 1861, the CSA printed its own money and circulated it in the form of promissory notes called 'graybacks'; the holders of these notes were promised to get gold/silver once CSA won the war.
As the south lost the war, the value of these notes reduced drastically, causing inflation in the economy as prices of goods increased largely.

Later in 1865, the CSA surrendered and the currency lost its value completely

It was the most widespread war in history, with more than 100 million people serving in military units.In general, countries involved in the war, directly or indirectly, faced increased financial demands to support military efforts and related activities. These demands often exceeded the regular revenues collected through taxes and other means.  To cover these expenses, governments, including Argentina's, resorted to printing more money. This  leads to inflation if the amount of money in circulation grows faster than the economy's capacity to produce goods and services, as it increases the demand for goods without a corresponding increase in supply, leading to higher prices.

For Argentina, the decision to print money was influenced by the need to finance the economic and military demands of the war period, despite Argentina's official neutrality for much of WWII.