Juan Yagüe y Blanco, 1st Marquis of San Leonardo de Yagüe was a Spanish military officer during the Spanish Civil War, one of the most important in the Nationalist side. He became known as the "Butcher of Badajoz" because he ordered thousands killed, including wounded Republican soldiers in the hospital.

The Spanish Civil War was a military conflict fought from 1936 to 1939 between the Republicans and the Nationalists. Republicans were loyal to the left-leaning Popular Front government of the Second Spanish Republic, and consisted of various socialist, communist, separatist, anarchist, and republican parties, some of which had opposed the government in the pre-war period. The opposing Nationalists were an alliance of Falangists, monarchists, conservatives, and traditionalists led by a military junta among whom General Francisco Franco quickly achieved a preponderant role. Due to the international political climate at the time, the war had many facets and was variously viewed as class struggle, a religious struggle, a struggle between dictatorship and republican democracy, between revolution and counterrevolution, and between fascism and communism. According to Claude Bowers, U.S. ambassador to Spain during the war, it was the "dress rehearsal" for World War II. The Nationalists won the war, which ended in early 1939, and ruled Spain until Franco's death in November 1975.