The German occupation forces arrived at Rønne Harbor on 10 April 1940 late in the afternoon and not, as in the rest of Denmark, on 9 April early in the morning. Initially, the occupying forces were accommodated at Missionshotellet (where Hotel Hoffmann is now located) and at Dams Hotel (the current Dams Gård). Østre Skole was also seized for accommodation, but a few days later the Germans moved to Knudsker Skole. Already in mid-May, the German infantry battalion left Bornholm and was replaced by half a hundred naval personnel, who were headquartered at Missionshotellet, but had small diversions at the ports of Nexø, Svaneke, Allinge and Hasle. The German Inselkommandant had his headquarters at the Missionshotellet, while the changing crew was gradually accommodated at the Hotel Phønix.

Gradually, Bornholm became the base where German naval personnel recuperated, for example after the long and strenuous submarine tours in the Atlantic. With both German and Danish authorities there was a desire to have the German troop units located outside Rønne, and in May 1941 a lease was entered into (paid by Denmark) regarding a 2.5 ha large area on Galløkken, where the occupying power could then build a barracks camp. The camp was to house the Inselkommandanturen, signal station, accommodation area, infirmary, mess and canteen facilities, garage and stables, and even prisons, which a number of Danes also got to know. When construction began, it was an advanced, modern element construction with standard German wooden elements, which were so cleverly designed that the individual buildings could be erected in any imaginable size and design as needed. The preserved hostel building is an example of this. On 30 August 1941, the Inselkommandan sent out invitations to the camp's inauguration, and in October 1941 it was fully operational. There is a diary entry stating that the people of Bornholm strewed drawing pins on the cycle paths to the camp, so that the cycling German soldiers could puncture. It was early sabotage.

On 29 August 1943, the political break occurred between the highest authorities of the German occupying power in Denmark and the Danish government, which resigned. The barracks and establishments of the Danish army and navy were defeated and occupied. This morning, Bornholm's county commissioner, together with the commander and the chief of police, had to attend a meeting with the Inselkommandanten, presumably in the building that has been preserved here. On 4 September, the Inselkommandanten gathered the Bornholm officers and two arrested Bornholm resistance fighters in the officer's mess (this building) and gave permission to call home for civilian clothes, as they were to be taken to Copenhagen at night as prisoners of war. On 1 September 1944, the then Inselkommandant hinted that more barracks would be built, but this was never carried out. On 27 January 1945, the Danish police officers arrested on Bornholm were taken to the camp at Galløkken, but they were quickly released again. In mid-March 1945, around 1,000 very young recruits arrived on Bornholm. Some were accommodated and trained at Galløkken. In the last days of April and the first days of May 1945, the Galløkke camp was crowded with the remains of torn up German units fleeing from the Eastern Front. A number of missing and mostly sick civilian refugees from the Eastern regions had also escaped into the camp.

On May 5, 1945 - Denmark's Liberation Day, by the way - a deeply tragic scene took place in this building. A standard court was set up to try a lieutenant colonel who had come from the Eastern Front with his badly torn up anti-aircraft division. He had made a defeatist statement which did not fit into the Nazi system. The sentence came down to execution the next morning at 08:00. The lieutenant colonel spent his last night in the Kasteltårnet and on May 6 at 08:00 executed by firing just west of the tower.

9 May 1945, late in the afternoon, five Soviet Russian motor torpedo boats entered Rønne Harbor with the first contingent of the new occupation force on board. The Soviet Russian officers were immediately driven by the resistance movement to Galløkken, where the Inselkommandanten and the high-ranking general were taken as prisoners and immediately taken to Kolberg. From 9 May 1945, the Soviet Russians took over the Galløkkelejren. When they brought large quantities of straw and hay for horse feed and bedding, the camp gradually became a veritable rat's nest. The gall camp witnessed another macabre act. In the middle of the winter of 1946, the Soviet Russian forces on Bornholm were ordered to the camp, where the Soviet Russian general, after a thunderous speech, had two Soviet citizens executed for violating the Soviet Union's harsh laws of war.

On 5 April 1946, the last Soviet troops left Bornholm, and Danish army units were now accommodated in the camp mistreated by the two occupying powers. A Danish corporal, who was quartered in the camp with his company, said many years later at an anniversary speech that you kept up your marksmanship just by shooting rats!

In 1947, the Danish Defense Construction Service demolished the camp, and some elements of smaller barracks found e.g. use in the construction of the Almegårdslejren, now referred to as the Almegårds barracks. Some barracks were moved to the Landemærket - Borgmester Nielsens Vej area, where they served as accommodation for the foreign craftsmen during the reconstruction, some house savages and a small guard of Danish soldiers. The current Vandrerhjem, the old mess building, used by the armed forces, the Red Army and Danish forces, has been the setting for and witness to many significant and peculiar events both inside and outside its wooden walls.