Although Danish intelligence learned of the German plans to invade as early as 4 April, the accounts were contradictory, and in any case were not believed. Certainly, the Danes had no chance whatsoever of defeating the German invaders. The poorly trained and inadequately equipped Danish army numbered only some 14,000 men, 8,000 of whom had enlisted within 8 weeks prior to the German attack. The Danish navy consisted of just 2 small vessels and approximately 3,000 men. The navy surrendered without going on alert, allowing a German troopship to arrive at Copenhagen. The Air Force had only 50 obsolete planes and a handful of pilots, no match for the vaunted Luftwaffe.
On 9 April, German seaborne forces moved into the capital of Copenhagen and secured the city by 6:00 a.m. Meanwhile, German paratroopers conducted the first airborne operation of the war when they seized the undefended fortress of Madnes¿ and, shortly thereafter, the airport at Aalborg in north Jutland. At the same time, German army units raced across the Jutland Peninsula in motorized columns. Although Danish Army units briefly contested the Germans in north Schleswig, the outcome was never in doubt.
German minister to Denmark Cecil von Renthe-Fink presented an ultimatum to the Danish government, demanding surrender and threatening the destruction of Copenhagen by Luftwaffe squadrons already en route if it refused. There was absolutely no chance of victory over the Germans, and eager to avoid further loss of life, King Frederik IX and Premier Thorvald Stauning believed they had no choice but to order surrender at 7:20 a.m. The campaign for Denmark was over. Danish casualties amounted to 26 dead and 23 wounded; the Germans lost 20 dead and wounded.
The German invasion provided the excuse for the Allied occupation of Iceland, which belonged to Denmark. Allied possession of strategically located Iceland proved vital in the Battle of the Atlantic. German forces occupied Denmark until the end of the war in May 1945.
Deighton, Len. Blitzkrieg: From the Rise of Hitler to the Fall of Dunkirk. New York: Alfred A. Knopf, 1980.; Heiberg, Eric. Hitler's ‘Canary Bird': The German Occupation of Denmark in 1940. Master's thesis, Georgetown University, 1970.; Petrow, Richard. The Bitter Years; The Invasion and Occupation of Denmark and Norway, April 1940–May 1945. New York: William Morrow, 1974.