The Anti-Imperialist Front was set up in Ljubljana on 26 April 1941, two weeks after Slovenia, then a part of Yugoslavia, was occupied by Nazi Germany and ten days after the Yugoslav authorities in Belgrade surrendered.

It was renamed the Liberation Front in June, after Germany attacked the Soviet Union.

The organisation rapidly gained followers and represented a basis for a Partisan resistance movement which later became known as the National Liberation Movement.

Its founding meeting at the home of literary critic Josip Vidmar (1895-1992) was attended by representatives of the Communist Party of Slovenia, the Sokoli gymnastic society, the Christian Socialists and a group of intellectuals.

The movement was active in the entire territory populated by Slovenians, including where the Slovenian ethnic minority presently lives in Italy, Austria and Hungary, but, gradually, it started to be dominated by the Communists.

Celebrated in Socialist-era Yugoslavia as Liberation Front Day, the holiday has in recent years become a target of criticism from the political right, which argues for a more nuanced view of what it claims was the co-opting of a resistance movement by the Communists.