Which general led a revolution in Spain, overthrowing the newly formed republic?

The general who led a revolution in Spain to overthrow the newly formed republic was Francisco Franco. Franco's rise to power occurred during the Spanish Civil War, which lasted from 1936 to 1939. He was a nationalist leader who opposed the Second Spanish Republic, a democratic government established in 1931. Franco's forces, backed by fascist ideologies and supported by Nazi Germany and Fascist Italy, waged a brutal conflict against the republican factions, which comprised various leftist groups, including communists, socialists, and anarchists.

After years of intense fighting, Franco's nationalists emerged victorious in 1939, leading to his dictatorship that lasted until his death in 1975. Franco's regime was marked by repression of political dissent, censorship, and a return to conservative, traditional values in Spanish society.

The other individuals mentioned, such as Castro and Guevara, were primarily involved in events in Cuba rather than Spain. Salvador, without additional context, does not correspond to a significant historical figure relevant to the Spanish Civil War. Thus, Franco's actions were pivotal in shaping 20th-century Spanish history and the trajectory of its political landscape, making him the correct answer to the question.