The Schwerer Gustav and its sister cannon Dora were the two heaviest artillery pieces ever built in terms of overall weight (1350 tonnes) and projectile weight (15,700 pounds), with their 800mm rounds being the heaviest ever fired in battle. The weapons had a range of more than 24 miles. The weapons were initially intended to be used against the French Maginot Line, but the Blitzkrieg rendered that objective obsolete. Instead, the guns were used to fight the Soviet Union on the Eastern Front. During the German siege of Sevastopol in June 1942, the Schwerer Gustav saw action. 1)
The Karl-Gerät was intended to be a siege weapon, specifically to attack the Maginot Line. Its 21-man crew was capable of firing a 600mm heavy bunker-busting shell over three miles at a rate of roughly six shells per hour. There were a total of seven of these guns made — one as a test piece and six others that saw substantial battle on both fronts. The Karl-Gerät made its combat debut in June 1941, when a three-gun battery pounded the fortress of Brest-Litovsk during the first phase of Operation Barbarossa. The next year, in June and July of 1942, a battery of Karl-Geräts took part in the siege of Sevastopol. 2)
During World War I, the French created the Obusier de 520 train cannon. However, due to a sluggish acquisition process, the first gun did not reach the trails until late 1917, when a shell detonated prematurely and destroyed it. The second gun was constructed in 1918 but did not complete trials before the war ended, and therefore it was stored. The Obusier de 520 modèle 1916 had a range of nearly eight miles and fired a 520mm projectile weighing over 3600 pounds. When Germany invaded France in 1940, the last gun was being refurbished for action when it was taken by the Germans while still in the workshop. 3)
The Japanese Yamato-class battleships were armed with the heaviest naval gun ever used in combat at sea, an 18.1-inch naval cannon. The cannons were capable of firing a 1.5-ton shell across a distance of 26 miles, and when installed in its turrets, the complete piece weighed as much as a standard destroyer of the day. Though both the Yamato and the Musashi were operational throughout the war, neither deployed their Type 94 weapons until near the end. 4)
During World War I, the British 18 inch Mk I was conceived and manufactured, and it was installed on the HMS Furious. The Furious, on the other hand, was transformed during construction, and two of its three turrets were installed on two Lord Clive-class monitors. Despite being slightly smaller than the later Japanese Type 94, the Mk I's shell weighed more (3320 pounds). The guns were used late in the war, with one shelling a railway bridge in August 1918 and the other firing ahead of advancing forces in October 1918. A third gun was also built, although it was never used during the war. 5)
Big Bertha, also known as the German Dicke Bertha, was a type of 420-mm (16.5-inch) howitzer employed by the German army to attack Belgian and French forts during World War I. The gun was officially known as the 42-cm kurze Marinekanone 14 L/12 in Räderlafette (“42-cm short naval canon 14 L/12 on wheeled carriage”), but German soldiers dubbed it “Big Bertha” after one of its shells completely destroyed Fort Loncin during the siege of Liège, Belgium. A total of 12 Big Berthas were deployed. 6)
The 42 cm Gamma Mörser, also known as the 42 cm kurze Marinekanone L/16 (German for “short Naval cannon with 16 caliber barrel”) during WWII, was a German siege howitzer. Before World War I, Krupp created a series of super-heavy siege cannons. The gun was employed to attack the Kaunas Fortress during the conflict. The only cannon that survived World War I was deployed to attack the Maginot Line and the fortress of Sevastopol in World War II. 7)