Why the Allies and the Nazis learned opposite lessons from the first major airborne invasion in history

Nazi Germany paratroopers Fallschirmjagers
German paratroopers landing on Crete during Operation Mercury, May 20, 1941.

  • The German invasion of Crete in May 1941 was the first major invasion led by paratroopers.
  • It was a costly victory for the Germans, which led Hitler to dismiss such operations in the future.
  • But the Allies saw the importance of paratroopers and invested heavily in their use during the war.
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Early on May 20, 1941, thousands of German paratroopers, known as Fallschirmjägers, in hundreds of transport planes and gliders were preparing to assault the Greek island of Crete.

It was the first time a large-scale invasion was spearheaded almost entirely by paratroopers. The battle was the final part of the Axis invasion of Greece, and on paper, the numbers favored the Allies.

Germany’s 22,000-man invasion force was up against a combined British Commonwealth/Greek force of about 42,000, the Royal Navy was much stronger than its Axis counterparts in the Mediterranean at the time, and the only way Germany could win was by capturing Crete’s three airfields with Fallschirmjägers.

British intelligence knew this before the battle and told the commander on the island, Maj. Gen. Bernard Freyberg. When the Fallschirmjägers landed, they encountered intense resistance, but after a brutal 13-day slog, the Germans took the island.

The victory came at a huge price for the Fallschirmjägers – so much so that Hitler soured on large-scale airborne operations, remarking that “the days of the parachute troops are over.”

The Allies, meanwhile, learned the complete opposite lesson.

A costly victory

Nazi Germany paratroopers Fallschirmjagers
German paratroopers on their way to the cargo planes before their jump into Crete, May 20, 1941.

By the time Crete was invaded, the Fallschirmjägers had earned a reputation as elite soldiers, having assaulted air fields and strategic positions in Denmark, Norway, the Netherlands, and Belgium.

At Crete, they would seize the island’s three main airfields, whereupon the rest of the invasion force would be airlifted in. Small amphibious landings were also planned, but the airfields were the prime objective, making the Fallschirmjägers the key to victory.

But the German victory at Crete was due as much to Allied communication and leadership failures as it was to the skill of the German paratroopers.

British soldiers bayonets Crete
British soldiers with fixed bayonets in a trench on Crete, May 1941.

Freyberg was convinced that the real German invasion would come from the sea and positioned most of his forces along the coasts, neglecting to properly defend or sabotage the airfields. Even when the airfields were under attack, Freyberg refused to commit his reserves to their defense.

Capturing the airfields was still difficult and costly for the Fallschirmjägers- only one of the three was taken, and only after high German casualties.

When the battle was over, Germany and Britain had both suffered over 3,000 killed.

About half of the British losses came from the Royal Navy, which lost eight ships to Luftwaffe air attacks. The Germans also lost 146 aircraft (mostly transports) destroyed and had another 165 damaged.

Inferior airborne equipment

Nazi German paratroopers parachutes
German paratrooper volunteers board a plane during military training, June 23, 1938.

A major reason Fallschirmjäger losses were so high was their equipment. German parachutes were based on an old Italian design and didn’t have risers, which meant Fallschirmjägers could not steer or change course in the air and had no control over where they landed.

The design of German parachutes also tended to force Fallschirmjägers into hard landings at dangerous angles, increasing the chances of fracturing or breaking bones far higher than those of Allied paratroopers.

German parachutes also did not have a quick-release system, which meant they could drag German soldiers along the ground if caught in high winds before they were fully detached, or leave them stuck for longer periods of time if they landed in trees.

Nazi Germany paratroopers Crete
German paratroopers take cover behind a wall during an advance on Crete, May 1941.

Finally, because they jumped at lower altitudes than Allied paratroopers and had poor parachute setups, almost all Fallschirmjägers jumped without their primary weapons, carrying only pistols or knives. Instead, their armaments were dropped in canisters that the paratroopers had to retrieve once on the ground.

These defects had disastrous consequences for the Fallschirmjägers at Crete. Many were killed before they even had a chance to fight.

On a number of occasions, Cretan civilians swarmed and killed Fallschirmjägers who were stuck in trees or didn’t have guns. Such widespread civilian resistance was a first for the Germans, and led to many reprisal killings after the battle.

Lessons learned

Nazi German paratroopers Italy
German paratroopers during their rescue of Italian dictator Benito Mussolini, in Italy, October 2, 1943.

Fallschirmjägers continued fighting after Crete. They conducted a number of smaller jumps around Europe, including as part of the Battle of the Bulge. For the most part, however, they were used as elite ground-based infantry.

Although they had lost the battle and inflicted heavy losses on the Fallschirmjägers, the Allies recognized the importance of paratroopers and invested heavily in perfecting the deployment of airborne infantry.

Allied airborne assaults were conducted on a much larger scale, usually in conjunction with a larger ground or amphibious assaults that paratroopers could link up with. American and British paratroopers also had much better parachutes and jumped fully equipped for battle.

The superiority of Allied paratroopers was demonstrated on D-Day in June 1944, when over 18,000 paratroopers jumped behind enemy lines in Normandy. Despite being scattered and confused after the jump, and without much of their equipment, groups of paratroopers were able to regroup and accomplish many of their objectives.

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The hunt for Germany’s largest warship proved that U-boats were the Nazis’ best weapon

Nazi Germany navy battleship Bismarck
The German battleship Bismarck after its completion but before it received its camouflage paint.

  • Early in World War II, Nazi Germany used its navy to isolate Britain from resupply by sea.
  • Germany capital ships, like the battleship Bismarck, were an important part of that strategy.
  • But it was Bismarck’s destruction in May 1941 that solidified U-boats as Hitler’s weapon of choice.
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On the night of May 18, 1941, the German heavy cruiser Prinz Eugen steamed out of its base at Gotenhafen (now Gdynia, Poland), followed five hours later by the Kriegsmarine’s crown jewel, the battleship Bismarck.

Bismarck and Prinz Eugen were on a mission to wreak havoc on British merchant shipping. German U-boats were already very effective at this, but Grand Adm. Erich Raeder, head of the Kriegsmarine, hoped to demonstrate to Hitler the value of Germany’s surface fleet in order to avoid future budget cuts.

What followed was one of the most intense naval searches in military history, the result of which convinced Hitler that U-boats, not capital ships, were the Kriegsmarine’s best weapons.

Capital ships for commerce raiding

Nazi Germany navy battleship Bismarck
Bismarck off of Kiel, Germany, September 1940.

Britain was in a very desperate situation in May 1941. It had fended off the Luftwaffe’s relentless aerial onslaughts in the Battle of Britain but was still isolated and heavily reliant on supplies coming across the Atlantic.

The Kriegsmarine had been trying to block trans-Atlantic shipping routes since the war began, and its capital ships had played an important role in intercepting or sinking Allied shipping.

German surface ships also drew Royal Navy warships away from other duties, such as escorting convoys, and supported U-boats, which were then few in number.

Nazi Germany navy battleship Bismarck
Bismarck firing on a merchant ship in the North Atlantic in 1941.

Happy with earlier success in Operation Berlin, Raeder planned another commerce raid.

To maximize damage, the raid was to include Germany’s four best capital ships: battleships Scharnhorst and Gneisenau, which were sister ships, and Bismarck and its sister ship, Tirpitz.

But Scharnhorst and Gneisenau were damaged by constant RAF attacks while being repaired in port in France, keeping them out of action for months. Tirpitz’s crew was also still being trained.

Prinz Eugen, not as well armed or armored as a battleship, was the only available ship capable of accompanying Bismarck. Not wanting to delay the operation any longer, German commanders ordered the ships into the Atlantic.

Battle of the Denmark Strait

Nazi Germany navy Bismarck Prinz Eugen
Bismarck seen from Prinz Eugen in May 1941.

The mission, codenamed Operation Rheinübung, was led by Adm. Günther Lütjens, the commander of Operation Berlin.

Lütjens was ordered to focus primarily on merchant raiding and to avoid fighting British capital ships if possible. But Bismarck and Prinz Eugen were discovered by the Royal Navy, which attempted to intercept the ships as they sailed through Denmark Strait and into the Atlantic on May 24.

The British force consisted of the battleship HMS Prince of Wales and the battlecruiser HMS Hood, which was widely considered the pride of the Royal Navy.

The British ships were no match for Bismarck, which was newer and better armored. Bismarck and Prinz Eugen were able to fire full broadsides at the two British ships.

“When the big guns fired, the entire ship staggered,” Heinrich Kuhnt, a sailor on the Bismarck, recalled after the war. “It felt like it was bending. It was pushed sideways in the water. It was amazing.”

Minutes into the battle, one of Bismarck’s 15-inch shells hit one of Hood’s magazines. An enormous column of fire erupted from the battlecruiser, followed by a massive explosion that tore it in two.

“The ship broke into pieces,” Otto Schlenzka, a sailor on Prinz Eugen, recalled. “We were sure an explosion of that kind must have killed everybody.”

Hood went down with 1,415 sailors, all but three of its crew. Prince of Wales was also heavily damaged and had to withdraw. The Germans suffered no losses.

Bismarck’s end

HMS Ark Royal Swordfish
A flight of Swordfish torpedo bombers over British aircraft carrier Ark Royal in 1939.

Shocked by the violent destruction of the Hood, the Royal Navy committed nearly all of its available capital ships in the area to finding and destroying Bismarck.

Though it suffered no casualties in the battle, Bismarck received a number of hits that ruptured a fuel tank and caused flooding.

Lütjens, aware of the Royal Navy’s numerical superiority and of the danger of sailing a damaged warship, terminated the operation.

Prinz Eugen was ordered to continue commerce raiding on its own while the Bismarck headed for Nazi-occupied France.

Dorsetshire Bismarck survivors
Survivors from the Bismarck are pulled aboard HMS Dorsetshire, May 27, 1941.

Bismarck briefly evaded its pursuers, but a British reconnaissance aircraft, flown by a US Navy pilot, found it on May 26.

Subsequent torpedo attacks from Swordfish carrier planes disabled Bismarck’s rudder, forcing it into a continuous turn.

With the Royal Navy closing in, Lütjens sent a final message to Berlin: “Ship unmaneuverable. We shall fight to the last shell. Long live the Führer.”

On May 27, two British battleships and two heavy cruisers attacked Bismarck. They fired over 2,800 shells in a little less than two hours, hitting the German battleship some 400 times. Bismarck was left dead in the water.

The Germans detonated scuttling charges to sink the ship, while British heavy cruiser HMS Dorsetshire fired torpedoes to finish it off. Only 115 of Bismarck’s 2,221-man crew survived.

U-boat superiority

Nazi Germany navy U-boat submarine
A German U-boats, its crew on the deck and officers in the conning tower, arrives in Kiel, November 10, 1939.

Operation Rheinübung was a complete failure. Not only had the pride of the Kriegsmarine been sunk with nearly all hands, Prinz Eugen was unable to sink any merchant ships, meaning the primary objective was never achieved.

In the following weeks, the Royal Navy set about destroying the network German ships that refueled, resupplied, and rearmed German capital ships in the Atlantic. The result was the Kriegsmarine’s almost complete reliance on U-boats during the rest of the Battle of the Atlantic.

In the end, the U-boats were the Kriegsmarine’s most effective weapons. From September to December 1939, they sank 110 Allied vessels, while German capital ships only sank about a dozen.

Between July and October 1940, a period known as the “first happy time,” by German submariners, U-boats sank nearly 300 ships carrying over a million tons of cargo.

Between January and August 1942, the “second happy time,” U-boats sank another 600 ships carrying 3 million tons of cargo.

Hitler never ordered his capital ships into the Atlantic again, sending them to Norway or the Baltic instead. The Germans ramped up production of U-boats, which were easier to build than capital ships, and thousands of Allied ships were sunk before the war’s end in 1945.

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How a daring raid by Norwegian commandos kept the Nazis from building a nuclear bomb

Norway Nazi Germany World War II WWII
  • In late February 1943, nine commandos set out of daring raid against the Germans in the Norwegian wilderness.
  • Their mission, to destroy a plant producing heavy water, would fulfill one of the Allies’ most important goals: Prevent the Nazis from building an atomic bomb.
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At 8:00 p.m. on February 27, 1943, nine Norwegian commandos trained by the British Special Operations Executive (SOE) left their hideout in the Norwegian wilderness and skied several miles to Norsk Hydro’s Vemork hydroelectric power plant.

All the men knew about their mission was the objective: Destroy Vemork’s “heavy water” production capabilities.

Each man carried a cyanide capsule to take if they were captured and wore a British Army uniform so if they were killed and their bodies found, the Germans might spare the local civilians from reprisal killings.

Their mission would be one of the most successful in special-operations history, and it contributed to one of the Allies’ most important goals in World War II: Preventing Nazi Germany from developing nuclear weapons.

The race for an atomic bomb

Nazi Germany nuclear bomb weapons lab
The German experimental nuclear pile at Haigerloch, southwest of Stuttgart, being dismantled in April 1945.

Within months of the discovery of nuclear fission on December 17, 1938, the military potential of nuclear power became clear, and the race for an atomic weapon was on.

In April 1939, Germany started its nuclear-bomb effort, known informally as the Uranverein, or “uranium club.” It included some of the best scientists in the field, including the men who discovered nuclear fission and Nobel Prize-winner Werner Heisenberg.

During their research for a nuclear reactor, the scientists discovered that deuterium oxide, known commonly as “heavy water” because it has a heavier molecular weight than regular water, performed well as a moderator, enabling control over the fission process.

There was only one place in the world capable of producing heavy water on an industrial scale: Norsk Hydro’s Vemork hydroelectric power plant in southern Norway. The plant’s main purpose was to produce ammonia for nitrogen fertilizer; heavy water was actually a byproduct.

In January 1940, German officials asked to buy all of Norsk Hydro’s heavy water stock and if it was possible to increase the plant’s monthly output 10-fold to meet German demand.

This caught the attention of the French, who were experimenting with nuclear physics themselves and pursuing heavy water. Worried about German intentions, agents from the Deuxième Bureau, France’s military-intelligence agency, secured all of Norsk Hydro’s heavy water for France on March 9.

It was only a temporary setback for the Nazis. Exactly a month later, Germany invaded Norway and occupied it by early June. Vemork, now under German control, was forced to increase heavy-water production.

Operations Grouse and Freshman

Vemork Tinn Norway nuclear lab
The Vemork hydroelectric power plant, February 24, 2011.

The Allies, unaware of the German nuclear program’s progress, were increasingly worried that Germany may be ahead in the race. Vemork’s heavy-water production was known to be important to the program, and that alone was a good enough reason to take action against it.

Working with the Norwegian Resistance, the SOE created a plan for two teams to be dropped into Norway.

The first, codenamed Operation Grouse, was made up of four SOE-trained Norwegian commandos who would parachute into Norway, conduct reconnaissance, and secure a landing zone for a 34-man team of British commandos, codenamed Operation Freshman, who would land in two gliders and then assault the plant and destroy the 18 electrolysis cells that made heavy water.

On October 18, 1942, Grouse was launched. The team spent the next few weeks trekking to Freshman’s designated landing site, reaching it on November 9. On November 19, Operation Freshman was launched.

But Freshman was a colossal failure. Mechanical difficulties and bad weather caused one of the bombers and the glider it was towing to crash, killing the flight crew and a number of commandos. The second glider’s cable snapped when the bomber towing it aborted the mission, causing it to crash as well.

Survivors from both gliders were found by the Germans and executed as per Hitler’s Commando Order. Forty-one men were lost, security at Vemork was increased, and the Grouse team was stranded and had to fend for itself.

Operation Gunnerside

Norway Nazi Germany Norwegian Heavy Water Sabotage
A reconstruction of the Operation Gunnerside team planting explosives to destroy electrolysis chambers in the Vemork heavy-water plant.

Vemork was still a priority target for the Allies, and a new plan, with a stealthier approach, was developed.

A team of six Norwegian commandos would be dropped into Norway to link up with members of the Grouse team. They would infiltrate the plant, destroy the heavy-water production room with explosives, and escape into the night.

Codenamed Operation Gunnerside, the team parachuted into Norway on February 16, 1943, and linked up with the Grouse team on February 22. On the night of February 27, nine members from both teams set out for Vemork, with one member remaining behind to communicate with the British.

Upon arrival on the outskirts of the plant, they saw that the bridge, the only direct way into the complex, was heavily guarded.

The team had to descend a 328-foot cliff, cross a frozen river, then climb an almost 500-foot cliff before arriving at a fenced railway gate that led into the rear of the complex. They got there at 11:45 p.m. but had to wait for the guards to change shift, eventually cutting their way through the fence after midnight.

Once inside, the team split into two groups. Five commandos took covering positions outside the barracks, bridge, and main gate, while the other four entered the plant. Inside, they encountered only a Norwegian employee, who didn’t resist or raise the alarm.

Explosives were set in the target room, which was in the basement. The team evacuated and waited for the explosion. Because the room was so far underground and the walls were so thick, there was hardly any noise when the bombs went off, allowing the whole team to escape before the Germans found out what had happened.


Joachim Ronneberg Norway Gunnerside
Joachim Ronneberg, leader of Operation Gunnerside, at a ceremony in his honor in London, April 25, 2013. Ronneberg died in 2018.

The operation was a resounding success. The commandos destroyed the electrolysis cells and over 500 kg of heavy water. They managed to escape without firing a single shot or taking any casualties.

The Germans repaired the damage by May, but subsequent Allied air raids prevented full-scale production. Eventually, the Germans ceased all production of heavy water and tried to move the remaining supply to Germany.

In a last act of sabotage, a Norwegian team led by one of the Gunnerside commandos sank the ferry transporting the remaining heavy water on February 20, 1944, although at the cost of 14 Norwegian civilians.

The operations helped foil Germany’s nuclear ambitions, and the Nazis never built an atomic bomb or a nuclear reactor. Nazi Germany surrendered to the Allies in early May 1945, two months before the US’s bigger and better-resourced Manhattan Project tested the first nuclear weapon on July 16, 1945.

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