I can write about Yugoslav resistance movement. But I will give a broad picture so everything can be understood better.
Yugoslavia was under the dictatorship of King Alexander since 1929 and until his death (he was assassinated in Marseilles in 1934). Before and after that the Yugoslav "democratic" system was weak. For example the elections after 1934 looked like this: the voter came to the polling station where he had to say his name out loud and who he was voting for and then the members of the voting commission registered his vote.
There was also the great depression which affected Yugoslavia deeply, also the peasant population (more than 70 % of the population back then), there was civil unrest and many strikes in 1935-1936, there were also national tensions, primarily between Serbs and Croats. Also, communists existed (that will be very important later on) and had a great illegal network of operations because they were banned as a party and many of its members were assassinated by the government and many others were brutally tortured in what were basically concentration camps.
The state relied heavily on France and Britain (WW1 allies of Serbs), but in the 30's it also started leaning towards Nazi Germany, however each government tried its best to stay neutral in the European conflicts - but by 1941 the government gave up under the pressure and signed the tripartite pact with Italy, Germany and Japan. Massive protests of the population sprung up because of this and a coup was carried out by a Serbian general, backed by the Brits. This pissed of Hitler and Germany decided to invade Yugoslavia. The fighting was over in like 14 days, the army saw many sabotages (Croatians were killing their Serbian officers, Croatians officers gave up weapons immediately or instructed their soldiers to just go home). Yugoslavia was divided among Hungary, Italy and Germany and it basically ceased to exist de facto. The Germans and Italians also supported the Croat Ustaši and they supported their state NDH (Independend Croatian State), which was pretty much a puppet state. Similarly, all Slovenian "legal" parties decided they don't wanna fight against nazi and fascist occupation, but that they want to work together with them - but they didn't even get a puppet state, Slovenian lands were de jure and de facto incorporated into Italy, Hungary and Germany.
The communists were the only force that called out to the people to start an armed rPost too long. Click here to view the full text.