As a Spanish student currently studying the XX century I can give u some answers. As I said, I'm Spanish, so sorry if my grammar isn't the best.

Franco got the power after the civil War on 1939, which first objective was to finish with the II Republic asap, but some stuff happened(not getting into much detail) and it lasted 3 years more, until 1939 as I said.

Democracies, fascism and comunism signed on 1938 on England a "non intervention paper" Which obviously fascism and communisn didn't follow.

The civil was started on 1939, just few months after Spain finished his Civil War, and Franco tried helping Hitler, but obviously Hitler didn't want, because he just finished a Civil War, and Franco requested all the North part of Africa, which belonged to France.

After the WW II, Franco has a economy based on self sufficiency which didn't last very long, but, on 1953 Spain signed the "Madrid contact" Which gave USA 4 military bases in Spanish territory and Spain gained being considered as a "legal" Government, which leaded to the entrance of Spain in the "Marshal plan" And the "FMI(I don't know how to soy this in English sorry).

There obviously were some rebels who tried to stop the regime, but being so many casualties on the Civil War, Spain suffered from a demographic crisis, which lead to not so many people which had lived real democracy, but many young people didn't question the regime, that was called " The grey mass"(direct translation from Spanish), which wasn't keen on politics. Also, Franco introduced some updates to the regime, giving more rights to Spanish people.

Based on a right given on 1973, (the succession act), 2 years before Franco's death, he gave away the succesion act, which gave Juan Carlos, the grandson from Alfonso XIII, king before the II Republic (1902-1931) the authority to be the dictator of Spain. After Franco died, Juan Carlos I started an authoritarian monarchy, and being inconsistent he stablished a democratical system, which gave true rights to civilians and officially finishing the regime on 1977, where coup d'etat were tried to bring back a dictator, which didn't end well.

Finally, Spain was accepted at the European Union on 1986.

Sorry of I could answer all the questions you had, I'm just a well informed student and not a professor, not even have a degree on this topic.

Having more questions don't doubt and ask me and I'll try to answer them.

Key to answering your question is the 'frames' in which the Spanish Civil War and subsequent Francoist dictatorship were understood by the international political community and how those perceptions influenced foreign policy towards the Spanish regime. It is helpful to distinguish between several different periods:

1936-1939: In the period of the Spanish Civil War, there was a lot of contention surrounding the question of how to understand the conflict. Large conservative sections of European and American society supported Franco's 'fight against communism' whereas other groups, more left leaning/progressive, understood the conflict to be a 'fight against fascism' from the Republican government. What different groups understood the Francoist or the Republican factions were fighting for was more diffuse. Overly simplified: on Franco's side: a fascist society or a defence of traditional (Catholic) values? On the Republican side: (social) democracy or a communist/anarchist revolution? The ambivalence in how Franco was to be perceived/understood was already present during the war. In international politics, this ambivalence was most clear in the stance most European governments took towards the conflict: signing a non-intervention agreement which meant no aid or recognition was given to either party. (This was somewhat strange as one party was a democratically elected government and the other a coalition that had failed to launch a successful coup d'etat, a false equivalence.) As you mention, Nazi Germany and Fascist Italy actively supported Franco and there was definitely a close alliance between Franco, Hitler and Mussolini. The Soviet Union on the other hand supported the Republican government, albeit with a more complicated stance. Stalin actually did not want a complete communist revolution in Spain to occur but I'll not go into this in too much detail. Mexico was the only other country to aid the Republican government. If you want to read more about this period, I would highly recommend Helen Graham's The Spanish Civil War. A Very Short Introduction or Paul Preston's The Spanish Civil War: Reaction, Revolution and Revenge.

1939-1970s: After Franco successfully toppled the Republican government, Spain went through a period of executions and mass incarceration of political opponents, a political repression that would last throughout his entire rule. There were still guerilla groups from the republican side active until the 1960s, some operating from France initially and hoping the Allied powers would liberate Spain like they had with Nazi occupied territories. How much Soviet support they received, I cannot answer and I would be very happy to hear some recommendations for literature on the Spanish guerillas. During the Second World War, Franco never formally joined the Axis alliance but he was supportive of it. He initially declared Spain to be neutral when the war broke out but after France was invaded by Germany in June 1940, he openly supported Hitler both in words and actions.

Given the support of the Axis, after the war Franco's regime became rather isolated politically and economically. Franco was strongly associated with fascism and the aggression of the Axis during WWII. Spain was excluded from a lot of the process of European integration, both for being a former ally of Hitler and Mussolini and for not being a democracy. During the formation of the United Nations, the so-called 'Spanish question' arose and partly on the initiative of Mexico and with the support of the Soviet Union, Spain was excluded from becoming a member because it had supported Germany and Italy. During and immediately after WWII, the perception of Franco's regime as fascist was prominent. This can also be seen in the political/societal rehabilitation of foreign volunteers in the International Brigades in their home countries, who often became seen as the first ' anti-fascists'. Franco was initially responded to the rejection of the international community with a policy of strong nationalism and economic self sufficiency but this wasn't sustainable.

With the rise of Cold War tensions, Francoist Spain increasingly sought to assert itself as the 'first to recognise and combat the dangers of communism' as a way to rehabilitate itself. The United States increasingly aided Spain's rehabilitation into the international community, providing aid in 1953 and supporting the membership of several international organisations, in 1955 the United Nations. The tourism and film industry played an important part in the foreign policy efforts of the regime and it's worth looking into some literature on it, such as Franco sells Spain to America by Neal Rosendorff. The perception of Franco's regime as 'anti-communist' therefore often overtook 'pro-fascist' view at this stage. In nationalist propaganda and historical education in Spain, the fight against communism became a dominant narrative about the civil war.

Because Spain was not a democracy, it was not allowed to join NATO or the EEC (now EU). It did sign a trade preference agreement with the EEC but it was not granted assistance by an association agreement. Its relationship with Europe did gradually improve but its status as a dictatorship barred it from participating in European integration projects more closely.

1970s: When Franco died in 1975, the country had already gone through a lot of societal and economic changes and had a lot more international ties than after the Second World War. It gradually transitioned to democracy in the late 1970s and was therefore able to join the EU in 1986.

I have studied the Spanish Civil War for my research degree, that's why I can answer your question to some extent. I am happy to answer more questions or discuss this further.