In the 19th century, wars became the standard trigger for currency debasement. The U.S. Civil War introduced paper greenbacks; the Franco-Prussian War forced France off silver; the Russo-Japanese War pushed Russia off gold. The pattern was always the same: suspend metallic convertibility at the start of the war, over-issue paper during it, then fight a losing political battle over whether to return to the old standard. The United States returned to gold in 1879 — at great political cost. Argentina, Russia, and several European countries never fully returned. By 1914 the monetary system was held together by a gold standard that everyone knew was one war away from collapse.