It was over before most Danes had even finished their morning coffee. On April 9, 1940, the German invasion of Denmark became the shortest military campaign of the Second World War. Six hours. That is all it took for a sovereign nation to fold under the weight of the Wehrmacht. While the rest of Europe was bracing for years of grueling trench warfare or massive aerial dogfights, Denmark found itself in a surreal, "peaceful" occupation that historians still argue about today.
Basically, the Germans didn't even want Denmark for its land. They wanted the airfields in Aalborg. Why? Because they needed a "stepping stone" to get to Norway, where the real prize—Swedish iron ore—was at stake. If you look at a map, Denmark is just a thumb of land sticking up into the North Sea. For Hitler, it was a logistical necessity, a geographic speed bump on the way to a much larger fight.
The Morning the Sky Turned Green
Imagine waking up at 4:00 AM to the drone of low-flying planes. Not just a few, but hundreds. The Germans dropped leaflets called the Oprop!—written in a bizarre, broken mix of German and Danish—telling the population that the Wehrmacht was arriving to "protect" them from British aggression. It was a lie, obviously. But it was a terrifyingly effective one.
While the leaflets were fluttering down, German troops were already landing at the docks in Copenhagen. They literally walked off a merchant ship, the Hansestadt Danzig, and marched toward the Kastellet fortress. There was almost no resistance there. The Danish guards were caught so off guard that the Germans took the headquarters without firing a single shot that mattered.
Meanwhile, at the border in Southern Jutland, things were different. Real blood was spilled. Danish bicycle companies and motorcycle units tried to hold back armored cars. It sounds like a David and Goliath story, and it was. You had men on bikes with 20mm Madsen anti-tank guns trying to stop the German war machine. Sixteen Danish soldiers died that morning. It wasn't a lack of courage; it was a lack of time.
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Operation Weserübung: A Masterclass in Deception
The German invasion of Denmark was part of Operation Weserübung. This wasn't some haphazard land grab. It was a synchronized strike. While the army crossed the land border at Sæd and Kruså, the Kriegsmarine (the German Navy) was hitting various ports, and the Luftwaffe was seizing those critical airfields in the north.
The Danish government was stuck in an impossible position. King Christian X and Prime Minister Thorvald Stauning met with their top generals while the sounds of Heinkel bombers filled the air over the Amalienborg Palace. General William Wain Prior, the head of the Danish Army, actually wanted to fight. He argued that even if they lost, they had to defend their national honor. But the politicians knew better. They knew Copenhagen could be turned into rubble in a matter of hours. By 8:34 AM, the order to surrender was sent out.
Why Denmark Was the "Cream Front"
For the first few years, life in Denmark didn't change as much as you’d think. The Germans called it the Sahnefront—the Cream Front. Because the Danes had surrendered so quickly and cooperated, the Nazis let them keep their government. They kept their King. They even kept their own police force for a while.
This is the part that gets messy. To some, this was a brilliant survival strategy that saved thousands of lives. To others, it looked like collaboration. Denmark was feeding the German army. Huge amounts of Danish butter, bacon, and grain were shipped south to fuel the Nazi war effort. You’ve got to wonder: at what point does survival become complicity?
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The Turning Point in 1943
The "peace" didn't last. By 1943, the Danish resistance began to wake up. Sabotage against railways and factories became common. The Germans got tired of the "model protectorate" act and demanded the Danish government introduce the death penalty for saboteurs. The government refused and resigned.
That’s when things got dark. The Germans took over completely, martial law was declared, and the hunt for Denmark's Jewish population began.
The Greatest Escape in Modern History
If there is one thing everyone should know about the German invasion of Denmark, it’s what happened in October 1943. When the word leaked that the Gestapo was planning to round up all Danish Jews, the Danish people didn't just stand by. In a massive, spontaneous grassroots movement, they hid their neighbors in hospitals, attics, and basements.
Over the course of a few weeks, local fishermen ferried over 7,000 people across the narrow strait to neutral Sweden. It’s one of the few bright spots in an otherwise horrific era. While other countries saw high levels of collaboration in the Holocaust, Denmark managed to save over 95% of its Jewish population.
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The Scars That Remain
Even though the fighting only lasted six hours, the occupation lasted five years. It changed the Danish psyche. It created a deep-seated skepticism of military intervention that lasted for decades. You can still see the bunkers along the West Coast of Jutland—part of Hitler's "Atlantic Wall"—sinking slowly into the sand. They are concrete reminders of a time when Denmark was a "vassal state" in all but name.
Historians like Bo Lidegaard have argued that the Danish policy of cooperation was the only moral choice because it protected the people. Others, looking at the bravery of the Norwegian resistance, argue that Denmark should have fought longer to prove its democratic mettle. There is no easy answer.
Moving Beyond the History Books
If you're looking to understand the German invasion of Denmark more deeply, don't just read a Wikipedia summary. You need to look at the primary sources.
- Visit the Museum of Danish Resistance (Frihedsmuseet): Located in Copenhagen, it was recently rebuilt and offers an incredible look at the underground movement.
- Explore the West Coast Bunkers: Places like the Tirpitz Museum near Blåvand provide a haunting look at the German engineering that occupied the coast.
- Study the "April 9th" Movie: The 2015 Danish film 9. April is a stunningly accurate depiction of the bicycle infantry units in Jutland. It captures the confusion and the sheer disparity in power better than any textbook.
- Read the Oprop! Leaflet: You can find translations online. It’s a fascinating look at how psychological warfare was used to justify a blatant violation of international law.
The reality of 1940 is that Denmark was a small player in a very large, very violent game. The decision to surrender in six hours likely saved Copenhagen from the fate of Warsaw or Rotterdam. It wasn't a glorious moment, but it was a pragmatic one. To understand modern Denmark—its focus on diplomacy, its social cohesion, and even its specific brand of nationalism—you have to understand those six hours on a cold Tuesday morning in April.
Actionable Insights for History Enthusiasts
To truly grasp the nuances of this event, start by mapping the German advance. Look at the timeline between 4:15 AM (the first shots at Kruså) and 8:34 AM (the surrender). When you see how fast the Wehrmacht moved, the "collaboration" narrative starts to look more like a "no-win scenario." Check out the Danish Royal Library's digital archives for digitized photos of the German troops marching through Strøget; the faces of the onlookers tell you everything you need to know about the shock of that day.