Gustav Railway Gun (" Schwerer Gustav" or "Dora" ). German 80cm ( 31,5 inch) gun, weighed nearly 1,350 tonnes, and could fire shells weighing seven tonnes to a range of 47 km ( 29 miles). The gun was designed in preparation for the Battle of France, but wasnt ready for action at that time. It was later employed in the Soviet Union at the siege of Sevastopol. It was destroyed by the Germans near the end of the war in 1945 to avoid capture by the Red Army.