Muggles' Guide to Harry Potter/Books/Deathly Hallows/Connections
World War 2
In the article on Lord Voldemort, it is mentioned that Tom Riddle had been growing up at about the same time as the Nazi party in Germany had been gaining power, and beginning to espouse their ideas of racial purity. While it is pointed out there that Riddle, who we believe to have been a teenager during the hostilities, was far too young to take part in it, and that he would have refused to work alongside Muggles in any event, we also know that there may be a real-world connection.
We know from Harry Potter and the Philosopher's Stone that "the evil wizard Grindelwald" had fallen to Albus Dumbledore in 1945, and in an interview the author has said that this was related to the end of World War 2. Grindelwald's stated plan was to put Wizardkind at its "rightful" place, in charge, ruling the Muggles "for their own good". Dumbledore, in the letter that we have seen of his from that time, did emphasize that it was to be for the Muggles' own good. From what little we hear of Grindelwald's actions, we have to assume that the good of the Muggles was rather less on his mind than it was on Dumbledore's. What exactly the relationship was between Grindelwald's attempt to take power on the Wizarding side, and Hitler attempting to take power on the Muggle side, is of necessity uncertain. Detail on the events of Voldemort's rise to power do seem to be surprisingly close to the rise of the National Socialist party in Germany; the author has mentioned this similarity as well, though she notes that she was rather taken by surprise by this.
Mention is made of Nurmengard, the prison built by Grindelwald to house his enemies. Apparently, Grindelwald is the only prisoner therein when Voldemort queries him about the whereabouts of the Elder Wand. Parallels with Spandau Prison and the extended captivity of Rudolf Hess are inescapable, though as Hess died in 1987, and evidence within the story puts Grindelwald's death in 1997, there is no chance that Hess and Grindelwald are the same person.
It is likely that Riddle would have been watching Grindelwald's European war with interest, though it seems that he, with his hatred of Muggles, had seized upon the idea of Racial Purity as espoused by the National Socialist party, rather than Grindelwald's "greater good" policy. While Grindelwald's solution to the Muggle "problem" was to make them subjects, Riddle's was to wipe them out.
It is interesting to note a second connection, as well: the actions of the Ministry during Harry Potter and the Order of the Phoenix were, according to the author, quite consciously modeled on the government of the United Kingdom under Neville Chamberlain during 1938 and 1939.