On 6 April 1941, Yugoslavia was invaded by the Axis Powers. On that day, part of the Slovene-settled territory was occupied by Nazi Germany. On 11 April 1941, further parts of the territory were occupied by Italy and Hungary. The Germans occupied the Upper Carniola, the Lower Styria, the northwestern part of Prekmurje and the northern part of the Lower Carniola. The Italians occupied the Inner Carniola, the majority of the Lower Carniola and Ljubljana, whereas the Hungarians occupied the major part of Prekmurje, which prior to WW1 belonged to Hungary. Resistance by the Kingdom of Yugoslavia's army was insignificant. In 2005, Slovene authors first published information about six villages in Lower Carniola that were annexed by the Independent State of Croatia, and a Maribor-based historian first published original research about it in 2011, but it remains unclear why the villages from Drava Banovina were occupied contrary to a known German-Croatian treaty.