[1] Established in April 1943, its leaders included Josef Søndergaard, its "central figure",[2] Jens Lillelund, and brothers Jorgen and Mogens Staffeldt.

[1] For the initial several months, Holger Danske obtained explosives and training from the Danish resistance movement group Borgerlige Partisaner (BOPA), a Socialist organisation.

[2] The organisation was then associated with the British Special Operations Executive (SOE) and the Freedom Council that coordinated efforts with Holger Danske and the Danish resistance movement group BOPA.

[6] Holger Danske bombed the Forum Copenhagen on 24 August 1943 by delivering bottles of Tuborg lager packed on top of plastic explosives.

[9] As resistance groups became more effective, Joachim von Ribbentrop (Nazi Minister for Foreign Affairs during World War II), ordered a state of emergency in Denmark.

The Danes maintained some control when Nils Svenningsen led Danish civil servants in running the country under the direction of the Germans.

[10] The Gestapo "conducted a long series of arrests" of Holger Danske fighters, including Nordisk Boghandel and brothers Morgens and Jørgen Staffeldt.

[14] Lillelund met with leaders of the Freedom Council and BOPA to develop a plan to use flying squads to leave a site after sabotage quickly.

[16] After a general strike in the summer of 1944, there was a lull in sabotage activities while members began to train for military action against the Germans.

[17] In Jutland and the provinces, Holger Danske sabotaged rail lines that had been used to transport people and equipment from Germany to Denmark and Norway.

As the Germans planned their activities, they coordinated their efforts with the Danish State Railways (DSB), which informed the resistance organisation.

[18] Two of the members of Holger Danske were Jørgen Haagen Schmith and Bent Faurschou Hviid,[1] who became famous under their aliases, Citronen (the Lemon) and Flammen (the Flame).

One member of the group, Lis Mellemgaard, survived the war as she remained at home with a sore throat when her colleagues were rounded up and executed in March 1945.

[21] A woman named Klinting had worked for German employers and was a saboteur who obtained and destroyed plans for new Luftwaffe aircraft.