The Danish Underground was already starting to grow by late 1941. On 16 September 1943, the “Freedom Council” was established, which began to organize orderly underground activities. Several Underground Groups formed, and among them one that was created by the Communists. Activity on the ground intensified, and towards the day of the Invasion of Normandy railroad tracks in the Jutland Peninsula were sabotaged in order to prevent the transfer of Forces by train from Norway to the Battle Theatre. The Underground also engaged in the publishing of an extensive Underground Press, while the Council dealt with gathering Intelligence that contributed greatly in the area of the V-1 Rockets.
Overall, about 800 people operated in the Underground.
Towards the likely Allied invasion of the Continent, a Danish Brigade was organized and trained in Sweden. It numbered about 5,000 persons who had been recruited from among refugees residing there. A number of Jews, who had been previously smuggled into Sweden, also volunteered to this Brigade and in early May, 1945, they returned to Denmark, donning uniforms. Some of them even reached Eretz Israel later and took part in the War of Independence.
The Underground grew larger and larger, and by May, 1945, numbered approximately 40,000 people, who included, among others, former members of the Military and the Police. With the German surrender, on 4 May, the Underground took control of the Government in Denmark.
One of the famous Missions conducted by the Danish Underground was the evacuation of the Country’s Jewish population. In an organized operation, the entire population, numbering about 7,000 human-beings, was transferred to Sweden in the course of a single night. Of those people, 472 were caught and sent to the Theresienstat Camp, and 52 of them died.