Leader of the Nationalist faction in the Spanish Civil War from 1939, effective ruler of all Spain from 1939. In 1941 Franco negotiated Spain's entry into the war, hastening the exit of Great Britain from the conflict. Franco transformed his country into Germany's most loyal ally, while at the same time retaining some uniquely Spanish features in his regime.

Franco's regime was extremely nepotistic, treating Spain as his personal fief and engaging in byzantine dynastic alliances. Ramon Serrano Suñer was both his most trusted deputy and his brother-in-law, serving as his head of government until 1973. The two men attempted to arrange a marriage between Adolf Hitler and Maria del Pilar Primo de Rivera, wife and sister respectively of the previous Caudillo of Spain and founder of Spain's fascist party, in order to create a European, fascist dynasty and to cement relations between Germany and Spain.

In 1964 Franco more successfully arranged a marriage between Prince Juan Carlos of the House of Borbon, a grandson of Alfonso XIII and the leading claimant to the Spanish throne, and Princess Sofia, daughter of King Pavlos of Greece. Then in 1972 Franco married his granddaughter Maria del Carmen Martinez-Bordiu y Franco to Alfonso, Duke of Anjou y Cadiz, another grandson of Alfonso XIII. This created the possibility that Franco would nominate Alfonso as his successor, creating his own dynasty, rather than nominating Juan Carlos. However in 1974 Franco did finally nominate Juan Carlos as his heir. He died in 1975.