The V-3: Hitler's Super Cannon

A prototype of the V-3 at Laatzig, Germany, in 1942.(Bundesarchiv CC-BY-SA 3.0)

The Third Reich produced a number of "Vengeance" weapons during WWII. Most people are familiar with the V-1: the first ever cruise missile and the V-2: the first ever ballistic missile used in war. There was a lesser-known third Vengeance weapon the German's deployed, however. It wasn't a missile, but a gun. A really big gun. So large some people called it a "Super Cannon."

The story of the V-3 Super Cannon actually goes back to WWI. During that war, the Germans came up with several guns that pushed cannon technology at the time to its limit. One of these devices was officially named the "Kaiser Wilhelm Geschütz," gun, but was better known by the moniker "The Paris Gun." The Paris Gun had the longest barrel of any piece of artillery used during WWI. It was capable of launching a 234-pound projectile up to 81 miles. In March of 1918, the Germans parked several of these weapons about 75 miles away from the city of Paris and started bombarding it. The cannon was so distant from the metropolis that it couldn't be heard and the populace at first thought they were being bombed by high-attitude zeppelins.

While this gun was successful in terrorizing the citizens of Paris, it wasn't extremely effective as a military weapon. The shell was relatively small and the accuracy was low enough that it couldn't be directed against any particular asset (like a munitions factory). The gun also suffered from a number of problems that plague all designs of very large cannons. First of all, in order to get the shell up to the speed necessary to send it over 80 miles, the barrel of the gun had to be impractically long. The Paris gun's 111-foot (34m), long barrel was so big that it sagged and needed support cables to keep it straight. Also, the charge to drive the shell out of the long gun was so large and the force applied by the shell as it raced up the barrel was so high, that it eroded the interior of the barrel with each shot. Each shell had to be slightly larger than the one before it to compensate for this, and after 65 shots, the barrels had to be sent back to the manufacturer to be redone completely.

A patent drawing by Haskell showing a cross-section of the gun with the multiple chambers.

Even with all these disadvantages, however, the French were impressed with Germany's ability to bombard a target at a great distance. The French military were soon working on plans to build their own super cannon. They wanted a super cannon that would have the range of the Paris gun, but without all the problems.

Designing a Super Cannon

Munitions designers had actually been thinking about these issues for more than a half century before WWI. In the late 1850's two U.S. men, Azel Storrs Lyman and James Richard Haskell, collaborated on a plan for a gun that would allow the shell to be accelerated to extreme speeds without the need of a single, huge, destructive charge at the base of the weapon to propel it. In their design, a normal-sized charge would be set off at the base of the barrel and as the shell moved up the barrel it would pass side chambers with additional supplemental charges. As the shell passed by these chambers, the charge in each would be set off. This would allow the pressure behind the shell to be kept high as it accelerated out of the barrel without using a large, single, damaging charge at the base.

A test version of the "Lyman-Haskell multi-charge gun" was constructed at the Frankfort arsenal in Philadelphia, PA, on the instructions of the U.S. Army's Chief of Ordnance. Unfortunately, the designers ran into some problems. They were depending on the heat from the initial charge to set off the supplemental charges as the shell passed each one of them. Unfortunately, the seal between the shell and the barrel wasn't complete and hot vapors leaking out in front of the shell would set off the supplemental charges early. This actually had the effect of slowing the shell down a bit instead of speeding it up. Eventually, Lyman and Haskell abandoned their work.

But they were not the only ones who had come up with this idea using multiple charges. In France, engineer Louis-Guillaume Perreaux was working on a similar gun at almost the same time as Lyman and Haskell. In 1864 he was granted a patent for this multi-chamber weapon and later exhibited it at the 1878 World Exhibition in Paris.

In 1918, when the French found themselves on the wrong end of the Paris gun, they started researching long-range cannons using this same multi-chamber idea. Before they could finish a prototype, however, the war ended, the project was shelved, and the plans for this super cannon were locked away in an archive.

Hitler's Super Cannon

When WWII started and France fell to the Germans in 1940, Hitler's troops raided the archive and the plans fell into the hands of August Cönders, a German weapons designer. He was intrigued with multi-chamber design and felt it might be just the mechanism he needed to build a gun that could launch a shell an unheard of distance.

Cönders built a prototype of the gun using standard 20mm anti-aircraft gun barrels. It seemed to work, so it was presented to Albert Speer, the Minister of Armaments and War Production, as a way to fire rounds across the English Channel into London from the shores of France.

Two U.S. soldiers pose with a captured V3 finned projectile.

With that goal in mind, Cönders was given the money to build a larger prototype at the proving ground near Magdeburg. Here he ran into some problems. Like Lyman and Haskell, vapors were sneaking past the shell and setting off the supplemental charges early. A piston-like device was designed and placed between the primary charge and the shell to seal the barrel. This took care of the problem.

To hide its true goals, the project was given the name Hochdruckpumpe which means "High Pressure Pump" (sometimes referred as "HDP"). It was also later known by the name Fleißiges Lieschen which means "Busy Lizzie."

To further reduce the damage to the barrel during firing, it was decided the shells would be stabilized in flight by giving them fins. Most shells fired from guns contact the sides of the barrel where a spiral groove gives them a spin as they exit the gun. This can quickly wear down the insides of the barrel especially if the projectile is moving very fast (this was one of the main problems for the Paris Gun). By using the fins, the wear on the barrel could be greatly reduced.

Fortress Mimoyecques

By September of 1943, the tests had been successful enough that Hitler approved the start of work on an operational site near the French town of Mimoyecques, about 5 miles from the channel. The location was on a steep, chalk hill. Slave laborers were brought in to tunnel through the rock and create a series of passages.

The site was designed not to house just one super cannon, but fifty. Hitler wanted to be able to bombard the city of London almost continually, and with so many cannons, he would be able to keep firing some while the others were being reloaded. It was estimated that installation, when in full operation would be able to bombard the city at the staggering rate of 300 rounds an hour. The plan called for two different complexes at the site, each with 25 guns. A single complex would consist of five tunnels, or drifts, that ran up at a steep angle under the hillside to where it emerged at the top. Inside these tunnels five cannons would be stacked on top of each other. An underground railway would supply both installations with shells and the explosives necessary to send the warheads the 103 miles across the channel to London.

Because the cannons would be so long (around 417 feet), they could not be aimed and would forever be fixed on London. Protected by thick concrete on top and heavy, armored doors over each drift when it was not in use, the Germans hoped Fortress Mimoyecques would be impregnable.

The remains of one of the firing ports of the V-3 cannons at Mimoyecques.

Such was not the case, however. The British were already taking a heavy interest in that section of France as the Germans were using it as alocation to launch their V-1 and V-2 rockets. When recon planes showed the Germans building a major installation at Mimoyecques, the British weren't really sure what they were doing, but it didn't look good to them. On July 6th, of 1944, they sent a squadron of Lancaster bombers to drop 11,900 pound "Tallboy" earthquake bombs on the location. Normal bombs would have gone off on the surface doing little damage to the concrete, but the Tallboys penetrated deep into the ground, creating an earthquake like effect and destroying the installation before it could ever fire a shot.

Luxembourg Bombardment

The destruction of Fortress Mimoyecques did not end the Germans interest in super cannons, however. Late in 1944, two smaller, super cannons with 160 foot long barrels were assembled near Trier, Germany. They were pointed at the city of Luxembourg 27 miles away which had been in Allied hands since September of that year. Operation of the guns was somewhat hampered by damage to the German rail system so that shells and the propellant charges were in short supply. Even so, the two guns fired 183 rounds before they had to be moved to avoid being captured. Of those 183 rounds, 142 hit the city, killing 10 people and wounding 35 others.

The Germans considered using the guns again during the war, but the effort to move and set them up turned out to be too great.

In the end, while the super cannon was a fascinating, technical achievement, it wasn't a very practical weapon. Unlike the V-1 and V-2 launch sites, these huge gun emplacements weren't at all mobile. Even if they had remained undiscovered until they became operational, the Allies would have soon ascertained their locations and they would have been subject to heavy air attacks that sooner or later would have put them out of business.

What remained of the Luxembourg guns was captured by the Allies and shipped to the United States to be studied before being destroyed in 1948.

Project Babylon

Even with the ineffectiveness of the German guns, interest in building a super cannon continued even to the end of the 20th century. In 1988, Iraqi president Saddam Hussein decided to build a series of "super guns" based on the work of Canadian artillery expert Gerald Bull. The project came to halt, however, when Bull was assassinated near his apartment in Brussels. Though no one has ever taken credit for the murder, rumors suggest that Israeli agents may have had Bull killed, fearing that his supergun might be used to lob shells at the Jewish state. The parts of the "Babylon" gun that had already been manufactured were seized by the British government and a piece of it can be seen at the Imperial War Museum in Duxford.

A diagram of the V3 site in France if it had become operational.

Copyright Lee Krystek 2017. All Rights Reserved.