World War II in Yugoslavia began on 6 April 1941 with the invasion by Nazi Germany. Soon after that, the Croatian part of the Žumberak Mountains became a part of the Independent State of Croatia (NDH), a World War II puppet state of Nazi Germany and Italy, with the western part being directly occupied by Italy. The Slovenian part was annexed directly to the Third Reich. The resistance movement in the Žumberak Mountains began when Partisans from 1st Zagreb Partisan Detachment came to this area. Matija Gubec Partisan detachment was established here in August 1941, However it was quickly destroyed. In 1942 partisans from Kordun managed to attract local people to join the resistance, so in 1942 Žumberak-Pokuplje partisan detachment was established. Later they merged with First Croatian proleterian battalion in famous XIII. proleterian brigade Rade Končar. That brigade managed to liberate Krašić in January 1943, which was a great victory for Partisan movement, since North-West Croatia was considered to be NDH stronghold. Many villages were completely burned and destroyed by the fascists, because their inhabitants allegedly helped the partisans. Žumberak was finally liberated on 9 May 1945, by the 10th division of Yugoslav People's Army.