A distinctive feature of the World War II artillery is the cannons with huge size and caliber that were used by some countries. Such weapon was the 914 mm Little David, constructed for the American army for attacking Japanese bunkers at the end of WWII. This mortar was the biggest in the world, but it was also never used in combat because Japan surrendered before its deployment.
[Image Source: Third Reich Colour Pictures]
Usage of these canons in 20th century began with the Big Bertha (also known as the “Fat Bertha”) during World War I. Big Bertha proved its effectiveness against older fortifications by destroying several Belgian and French forts. However, these cannons were almost helpless against newer constructions built of concrete reinforced by steel. This led to decreased usage of the 420 mm Big Bertha howitzers.
The German military industry wasn’t discouraged and new grand cannons were developed despite the Big Berthas failure. Karl-Gerät, also called Thor (like the Viking thunder god) and Mörser Karl, was developed between 1937 and 1940. It was self-propelled siege cannon that utilized 600 mm wide barrels. It fired projectiles weighing between 1250 and 2170 kilograms. The cannon had relatively short firing range of just 10 km with the lightest shell, but it was used with varying success between 1941 and 1945.
And now let’s take a look over the largest cannons ever used in battle. These are the 800 mm Schwerer Gustav and Dora, railway guns developed by the Krupp family company who also developed the Big Bertha cannons in WWI.
They were designed in the 1930s in order to destroy the strongest defensive facilities of their time – the Maginot Line in France. This defensive line was built by the French people along the frontier with Germany and consisted of different obstacles, concrete bunkers and fortifications, and weapons installations. For that purpose cannons should be able to destroy 1 meter thick layer of steel or 7 meter wide wall of reinforced concrete. When the war began, the Wehrmacht invaded France by passing through Belgium, thus escaping the Maginot Line and conquering France without necessity of destroying the defensive line.
Schwerer Gustav was 1350 tons heavy and was capable of firing 7 tons heavy projectiles at a distance of 47 km. Although not used to fulfill their initial purpose, the Gustav super cannons were transported to the Eastern front and participated in the Fall Barbarossa (Operation Barbarossa in German). During this operation the cannon was used for the siege of Sevastopol. After that it was transported near Leningrad (now Saint Petersburg) and started preparation for the siege, but the operation was cancelled. The gun was destroyed in order to avoid capturing.The Schwerer Gustav cousin – Dora, was intended to be used at the siege of Stalingrad. The menace of Soviet capturing forced German army to withdraw Dora from the siege. Dora was also destroyed before the end of the war.
Germans also had plans of building something that could be described as “self-propelled fortress”. The project was called Landkreuzer P. 1500 Monster and had to be powered by 4 submarine diesel engines. It was planned to be armed with Schwerer Gustav as main cannon and two smaller, 150 mm howitzers. The armament would have also included several 15 mm machine guns for air defense. The project was cancelled in 1943 and it remained on the drawing table only.