Is it ensure, insure, or assure?
A war fought in the late 1930s in Spain. On one side were the Loyalists, Spaniards loyal to a recently elected government in the form of a republic; on the other side were fascists (see fascism), led by General Francisco Franco. The Soviet Union sent aid to the Loyalists, some of whom were communists; the German and Italian fascist dictators, Adolf Hitler and Benito Mussolini, supported Franco. The Spanish fascists won the war and set up Franco's long rule of Spain as a dictator.
Note: Many Americans favored one side or the other in the Spanish Civil War, particularly people of left-wing sympathies, who supported the Loyalists. The Abraham Lincoln Brigade included Americans who traveled to Spain to fight in the Loyalist cause.