While bicycle troops might seem risible and impractical to modern eyes, such units were in fact quite common in many countries at the time, including Germany, fielding whole bicycle battalions. Early in World War Two, Japan conquered much of China and South East Asia employing some 50,000 bicycle infantry, such troops taking e.g. Singapore from Great Britain. Bicycle units were also employed by the British during the invasion of Normandy in 1944. Bicycle infantry was seen as cost effective mobility in place of e.g. horses, that needed extra feed and could panic under fire.
While a myth persist, that the German invasion of Denmark had been cleared in advance with the Danish government, no historians have ever been able to support that myth with evidence of such an agreement from neither Danish or German archives.
The German code name for the invasion of Denmark and Norway was "Weserübung"; "Weser" being the name of a river in Northern Germany, and "übung" meaning 'exercise'. Seperately, the invasion of Norway was labeled "Weserübung-Nord" ('W. North') and the invasion of Denmark "Weserübung-Süd" ('W. South').
The high caliber machine cannon used by the Danish motorcycle units is the 20 mm Madsen Autocannon M/38 mounted on Nimbus motorcycles. The light machine gun used by the infantry is the Madsen Recoil Gun with first models being produced from 1901. Both guns were exported in vast numbers by the Danish company Disa.
The first combat jump in military history using paratroopers was also commenced on April 9th, when German Fallschirmjägers were dropped at Aalborg Air Base and the Storstrøms Bridge. It was vital for the Germans to secure Aalborg Air Base in Northern Jutland for the Luftwaffe to refuel on their route to bomb targets in Norway, and the air base was in German hands and ready to fuel bombers before noon that same day.