Hungarian occupation of Yugoslav territories  The Hungarian occupation of Yugoslav territories consisted of the military occupation, then annexation, of the Bačka, Baranja, Međimurje and Prekmurje regions of the Kingdom of Yugoslavia by the Kingdom of Hungary during World War II. These territories had all been under Hungarian rule prior to 1920, and had been transferred to Yugoslavia as part of the post-World War I Treaty of Trianon. They now form part of several states: Yugoslav Bačka is now part of Vojvodina, an autonomous province of Serbia, Yugoslav Baranja and Međimurje are part of modern-day Croatia, and Yugoslav Prekmurje is part of modern-day Slovenia. The occupation began on 11 April 1941 when 80,000 Hungarian troops crossed the Yugoslav border in support of the German-led Axis invasion of Yugoslavia that had commenced five days earlier. There was some resistance to the Hungarian forces from Serb Chetnik irregulars, but the defences of the Royal Yugoslav Army had collapsed by this time. The Hungarian forces were indirectly aided by the local "Volksdeutsche", the German minority, which had formed a militia and disarmed around 90,000 Yugoslav troops. Despite only sporadic resistance, Hungarian troops killed many civilians during these initial operations, including some "Volksdeutsche". The government of the newly formed Axis puppet state, the Independent State of Croatia, subsequently consented to the Hungarian annexation of the Međimurje area, which dismayed the Croat population of the region. The occupation authorities immediately classified the population of Bačka and Baranja into those that had lived in those regions when they had last been under Hungarian rule in 1920 and the mostly Serb settlers who had arrived since the areas had been part of Yugoslavia. They then began herding thousands of local Serbs into concentration camps and expelled them to the Independent State of Croatia, Italian-occupied Montenegro, and the German-occupied territory of Serbia. Ultimately, tens of thousands of Serbs were deported from the occupied territories. This was followed by the implementation of a policy of "magyarisation" of the political, social and economic life of the occupied territories, which included the re-settlement of Hungarians and Székelys from other parts of Hungary. "Magyarisation" did not impact the "Volksdeutsche", who received special status under Hungarian rule, and in Prekmurje the Hungarian authorities were more permissive towards ethnic Slovenes.