Together with Anton Kokalj, Ernest Peterlin and Janko Kregar, Rupnik was also one of the founders of the Slovene Home Guard, an auxiliary military unit of the Wehrmacht, formed as a voluntary militia to fight the partisan resistance movement.
Zajedno s Antonom Kokaljom, Ernestom Peterlinom i Jankom Kregarom, Rupnik je bio jedan od osnivača Slovenskog domobranstva, pomoćne vojne jedinice Wehrmachta, ustrojenog kao dobrovoljna milicija za borbu protiv partizanskog pokreta otpora.