The "Espingol" - The Secret Weapon of 19th Century Denmark
During the two Slesvig wars of 1848-1850 and 1864, the Danish army employed a primitive automatic weapon and forerunner of the machine gun, the so-called "Espingol." It is unknown if this weapon ever received a different name in English. The espingol employed a unique form of rapid fire, and its magazine was muzzle loaded.

Rifle Fire Rockets
Although not widely known Denmark was heavily involvement in the "First Golden Age of Rocketry". Their development of a dedicated Rocket Corps and of manufacturing facilities put them, for a time, among the leaders of the nations who adopted Congreve's rocket system

V3
Called the V3, this was the "secret weapon" of the Danish resistance.