Between 6000 and 8000 Danes fought on the German side during WW2 - after the war about 3300 were convicted for this - about half of the volunteers were killed during their service on the Eastern Front.
The Germans began recruiting Danish volunteers shortly after the occupation of Denmark, but it wasn't until the invasion of the Soviet Union that the number of volunteers rose above 1000.
In June 1941 "Freikorps Danmark" was founded. Before then volunteers served in units like SS-Standarte Nordland, Regiment Danmark etc. Freikorps Danmark was to be a Danish unit, wearing Danish uniforms and led by Danish officers. But this was changed and the volunteers ended up wearing German Waffen-SS uniforms and was often led by German officers.
Frikorps Danmark was disbanded in the summer of 1943 and the soldiers were transferred to 11. SS-Freiwilligen-PanzerGrenadier-Division "Nordland".
The history of Freikorps Danmark
The history of 11. SS-Freiwilligen-PanzerGrenadier-Divsion "Nordland"