German invasion of Denmark (1940)

• 1. Introduction

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  The German invasion of Denmark on the 9th of April 1940 lasted approximately six hours, making it one of the shortest military campaigns of the Second World War. By the time most Danes had started their working day, their country had already fallen. What drove Germany to strike so swiftly at a nation with which it had signed a non-aggression pact less than a year before? And why did Denmark, a country with a real army, a navy, and a coastline backed by Allied powers, choose to lay down its weapons before noon?

• 2. Norway's Shadow

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  Denmark's own strategic importance to Germany was, by official assessment, limited. The invasion's driving purpose was Norway. Germany needed iron ore shipped from the port of Narvik, and to reach Norway it needed control of the airfield at Aalborg in northern Jutland. The Kriegsmarine also wanted to push the German sea-defence network northward, making it harder for British ships to approach from the north while attacking vessels in the Atlantic. Norway's fjords offered excellent submarine bases in the North Atlantic, and Germany intended to use them.

  To justify the operation, the Germans presented the invasion as a protective measure, claiming that Britain and France were on the verge of attacking both countries themselves. Beneath that pretext, the original German plan had been less extreme. The initial proposal was simply to pressure Denmark into allowing German land, naval, and air forces to use Danish bases. Adolf Hitler then escalated that demand into full invasion.

  On the 4th of April, five days before the attack, Admiral Wilhelm Canaris, chief of the Abwehr and himself involved in the German resistance to Nazism, passed a warning to the Danes that an invasion was coming. The Danish army knew the blow was imminent.

• 3. The Assault Unfolds

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  At 04:15 on the 9th of April, German forces crossed the Danish border at four points: Sæd, Rens, Padborg, and Krusaa. The alarm was sounded two minutes later, and the first Danish troops moved out at 04:35. The Kriegsmarine simultaneously landed forces at Lillebælt, cutting off Danish border units almost at the moment fighting began.

  At approximately 05:00, history's first paratrooper attack took place. Ninety-six Fallschirmjäger jumped from nine Junkers Ju 52 transport aircraft to secure Storstrøm Bridge, linking the island of Falster with Zealand. The elite German troops braced for a fierce defence of the coastal fortress on Masnedø island. Inside, they found two privates and one officer. Two hours after that, a platoon of paratroopers from the 4th battalion of Fallschirmjäger Regiment I dropped into Aalborg, the main city of northern Jutland. They met no resistance. Within an hour, German aircraft were landing at Aalborg in large numbers, and more than 200 landings and takeoffs were recorded that first day, most of them ferrying troops and fuel north to Fornebu Airport in Norway.

  At sea, the battleship Schleswig-Holstein put troops ashore at Korsør and Nyborg, severing connections between Funen and Zealand. Those troops reached Copenhagen by noon. At 03:55, a surprise landing at Gedser, Denmark's southernmost town, used the local ferry from Warnemünde, packed with German soldiers, who immediately cut telephone lines and advanced north.

• 4. Soldiers Who Fought Back

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  The Royal Danish Army had been warned of the attack but was denied permission to deploy or prepare defensive positions because the government feared provoking Germany. That left only scattered frontier guard units and elements of the Jutland division to face the invasion.

  At Lundtoftbjerg, the first clash of the campaign, a Danish anti-tank platoon with two 20 mm guns and a light machine gun held a road position. When a German column appeared at 04:50, the cannons opened fire on armoured cars and the machine gun targeted motorcyclists. A burning barn filled the road with smoke, slowing the German advance. The platoon eventually withdrew, but the Germans lost two armoured cars and three motorcycles. The Danes suffered one dead and one wounded.

  A few kilometres to the east at Hokkerup, 34 Danish soldiers built a roadblock from farm equipment in just twenty minutes. They knocked out the three lead German armoured cars and destroyed a German 37 mm gun with two shots. The Germans needed air support and roughly 100 men to surround and capture the Danish unit at 06:15. One Dane was killed and three wounded, one fatally.

  At Sølsted, fewer than 50 men of the Tønder garrison held a position against the German 11th Motorised Regiment. German infantry twice attempted to flank the Danes; both attempts failed under heavy fire. The regiment commander called in three Henschel Hs 126 aircraft, which bombed and strafed the position until the Danes fell back. The source records no Danish casualties there.

• 5. The Battle for Amalienborg

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  To secure Denmark's swift capitulation, German planners believed capturing Copenhagen was essential. At 04:20, a 2,430-ton minelayer escorted by an icebreaker and two patrol boats entered Copenhagen harbour with battle flags flying. Fort Middelgrund's coastal guns could have engaged it, but newly arrived recruits could not operate the weapons. A battalion of the 198th Infantry landed at 05:18, and German forces captured the 70-strong garrison of Kastellet, the headquarters of the Danish Army, without a single shot.

  Their next objective was Amalienborg Palace. The 198th Infantry Battalion advanced along three converging streets: Bredgade, Amaliegade, and Toldbodgade, intending to encircle the palace before a defence could form. What they did not know was that Kastellet's commandant, Christian Peter Bokkenheuser, had managed to alert the Royal Guard in his final moments before arrest.

  The Guardsmen were already in firing positions when the Germans arrived. The initial assault was repulsed, leaving three Guardsmen and four Germans wounded. Danish reinforcements arrived from Rosenborg Barracks carrying Madsen machine guns. A chaotic street battle spread across the entire quarter, with the fiercest fighting along Bredgade, and the German advance halted completely.

  That stubborn resistance bought King Christian X and his ministers time to confer with commander-in-chief General Prior. During those discussions, formations of Heinkel He 111 and Dornier Do 17 bombers from Kampfgeschwader 4 flew over the city, dropping OPROP! leaflets rather than bombs, but the threat was unmistakable.

• 6. Surrender and Its Reasoning

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  Facing the explicit threat of a Luftwaffe bombing raid on Copenhagen's civilian population, all voices in the room except General Prior favoured surrender. The argument was that Denmark's military position was structurally untenable: too small, too flat, and too exposed. Jutland was wide open to a panzer assault from Schleswig-Holstein. Unlike Norway, Denmark had no mountain ranges where a resistance could drag on for months.

  The government also weighed other options. A third path was exile, as the Czechoslovak government had taken. King Christian X and the Crown Prince refused to leave, however, partly because the Crown Princess was in the ninth month of pregnancy and could not travel. Denmark did hold water obstacles between the panzers and the capital, a long coastline, and a navy that could have sought Allied support.

  The Danish government ordered a ceasefire at 06:00 and formally capitulated at 08:34, in exchange for retaining political independence in domestic matters. The order infuriated the Royal Guard, who believed they could still expel the Germans from the capital. Some Guardsmen attempted to rearm themselves and assault Kastellet, where the Germans had established their temporary headquarters. Officers persuaded them to stand down by arguing that even if they drove out the initial troops, overwhelming German forces would follow.

  One unit refused the surrender order entirely. A colonel commanding the 4th Regiment at Roskilde believed the order had been coerced and wrongly assumed Sweden had also been invaded. He led his men onto the ferry at Elsinore and into exile in Sweden. When the misunderstanding was cleared up, most of those soldiers remained in Sweden and would later form the core of the Danish Brigade there in 1943.

• 7. Air, Sea, and Aftermath

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  The Danish Army Air Service was stationed at Værløse near Copenhagen when the invasion began. Plans to disperse the aircraft to airfields around the country had not been completed by 05:25, when Luftwaffe planes appeared over the base. One Fokker C.V-E reconnaissance aircraft was getting airborne when it was shot down by a Messerschmitt Bf 110 flown by Hauptmann Wolfgang Falck at an altitude of 50 metres. Both crew members died. The German Bf 110s then strafed the base under heavy anti-aircraft fire, destroying 11 aircraft and badly damaging another 14. The Danish Navy Air Service remained at its own bases and escaped unscathed.

  Once the fighting stopped, the German government presented the occupation as a peaceful one. Danish soldiers were disarmed that afternoon; those captured were allowed to return to their units. The day after the invasion, the island of Bornholm was occupied without incident. The Royal Danish Army was reduced to a 3,300-strong Life Guard unit. Approximately 240 Danish merchant ships abroad at the time of the invasion were incorporated into the Allied merchant navy, while ships in Danish ports served German iron ore transport.

  Casualty figures remain disputed. Author Kay Søren Nielsen, drawing on archives of the Danish weapons manufacturer DISA, cited claims of 203 German soldiers killed in Jutland, a number some historians regard as an exaggeration. A 2015 article in the Journal of Military History, Krigshistorisk Tidsskrift, placed actual German losses at 2-3 killed and 25-30 wounded, with 16 confirmed Danish military dead and 20 wounded. Military historian David T. Zabecki, writing in Germany at War: 400 Years of Military History, recorded 49 Danish casualties in total, with 20 German soldiers killed or wounded. The Danes later summed up the date with a phrase that endures: "Aldrig mere the 9th of April" - never again the 9th of April.