Biggest Rail Gun In World War II the Germans made use of huge railway cannons, Dora and her brother Gustav were the biggest and most effective. Dora only fired 48 shells in combat. It took 2000 men six weeks to assemble the gun ready for firing too, as it had to be assembled on-site on special tracks. In 1937 Hitler wanted a huge cannon that could destroy enemy targets such as fortresses at long range. The criteria required that the shell had to penetrate 7 meters of steel reinforced concrete or at least 1 meter of hardened armour plate over a range of 25 miles. The Maginot line was considered to be a worthy target, with the ability to blast it, whilst still within their own lines was too much of a temptation. A temptation so great that Hitler initially ordered three such guns to be built, regardless of how much manpower and resources they would use up in the process. Krupp steel industries was given the job of creating these huge guns and Professor Erich Muller worked out the mathematics need to manufacture them. He arrived at a caliber of 80cm - 31Â½ins with a shell of 7 tons and a barrel length of over 30 meters. They would have to be on a railway carriage split into to separate parallel tracks to disperse the weight estimated at over 1000 tons. The barrel would only be able to have vertical movement so the tracks had to be curved for the carriage to move on for sideways elevation. Specifications Of Dora And Gustav. Actual range achieved, 51,000 yards ( 29 miles ) crew of 250 for firing, crew of 2000 for full operation including loaders, train drivers, assembly workers, canteen workers, armed guards, mechanics, electricians and track maintenance. To operate Dora was similar to running a Battleship inland, all just to fire a big shell over distance. The biggest worry for the crew of Dora would have been attack from the air, so the gun would have needed high security, the best camouflage techniques and to have constantly been kept on the move. It would have been a great psychological win for the allies to have bombed her, the location of the gun sent by the resistance. Everything about Dora was massive including her ammunition, this consisted of a 7 or 8 ton 31Â½in shell. The shear weight of which meant that the gun had a very slow rate of fire, 2 rounds per hour with everybody working flat out was the limit. It was a big operation indeed to crank this thing up, but was it really worth it? The shells for Dora and Gustav, including the 1 ton charge was 17 feet long. It needed the ton of charge to send the 7 ton shell over 25 miles from the 100 foot long barrel. The shell on test firing proved to be able to penetrate 30 feet deep into earth making a crater over 90 feet across. The velocity of the shell was 2,700 feet per second, the barrel was estimated to 150 rounds, weighed 400 tons and the breach block where the shell was inserted weighed over 100 tons. Dora stood 5 stories high, over 20 feet wide 141 feet long and weighed 1323 tons, to say she was big would have been an understatement, she was absolutely mammoth, a behemoth of steel. To get some scale of the shell we see an image of an average sized guy at the Imperial War Museum in the UK standing next to one of Dora's 7 ton shells. If the Germans had utilized these to their best advantage then they may have made a difference in the tide of war. As it turned out though, they had little impact in one sense, even though they had great impact in another. At the beginning of January 1942 the gun was ready to go fully operational. Two railway engines were attached to the front of the gun carriage one on either side to slowly pull the carriage forwards on its curved track. This movement gave the gun the side elevation. The engines had a special ultra low gear to be able to move the carriage an inch forward at a time, for the best possible accuracy. I could imagine the scene "...up a bit...down a bit...left a bit...right a bit...ok...Fire......Achtung ! we missed ! " Dora was loaded slowly with huge winches and electrically powered rams by a crew of 250. The initial target for Dora was Sevastopol on the Eastern Front and in June 1942 the big gun opened fire. The gun was only fired over a five day period. A small spotter plane like a Storsch was used to fly over the target area and report back via radio with information on where the shells were landing. The trajectory with the relevant distance, gun elevation with projectile weight, velocity and other ballistics properties were mathematically and geographically worked out with slide rules, pencil and paper to accurately hit the target. The only calculators they used was the old grey matter ! Gustav attacked coastal gun batteries at a range of sixteen miles. It took eight shots to completely destroy these targets, Fort Stalin was destroyed later that day with only six shots. Fort Molotov was destroyed with seven shots on June 6th 1944. Nine rounds were fired at The White Cliff Of Severnaya Bay and a lucky shot hit an underground ammunition store and the whole Fort was completely destroyed. One of the shots missed the target and sunk a large ship in the harbor, the shell-burst must have been absolutely devastating. Seven shots were fired the next day in the same vicinity at nothing in particular, but was again used to more worth some days later when Fort Siberia was hit with five shots and destroyed as was Fort Maxim Gorki. As we can see, Dora did actually have some success and destroyed several targets with only a few shells. The barrel of the gun was worn out and Gustav had to be dismantled and shipped back to Germany to be re-fitted with a new barrel sleeve, this took weeks and weeks to do costing valuable time, effort and money, Germanys resources at this time was extremely pushed as it was. Dora did indeed destroy several targets as mentioned earlier, but were they worth the resources to actually do this? Had I been Hitler in WWII, I would not have wasted my resources on this project, I would have had another 500 Tiger tanks built instead. Dora was only fired several more times after the refit, this was due to the fact that she had to be disassembled, transported and re-assembled for every new target in different parts of enemy territory and the railway tracks had to be laid down for it each time. What a waste of time, money, manpower and overall resources, just for a few shots at the enemy. The total accomplishment of these guns was in respect quite small and did nothing to alter the course of the war for its owners. If anything, a pair of cannons like these would be more trouble than they were worth. Below is a 1/6th scale model of Dora that was home-made by Mr. Peter Shaw, in only 4Â½ months ! Even at 1/6th the original size, the scale of this Dora railway cannon is absolutley huge. Imagine a model compay making plastic kits in this scale, the box it would come in would be as big as a house and need a forklift truck to get it to your garden! As WWII was drawing to its inevitable conclusion of total victory for the allies, the Germans were in full retreat and as they retreated they destroyed every piece of equipment that they could not take back with them. The destruction of their equipment included the biggest cannons the world had ever seen...Dora and Gustav. One gun was destroyed with explosives in 1945 near Metzenhof, Bavaria by its crew as the allies were advancing. This marvel of engineering on the most colossal scale was rigged with explosives and then detonated, the resulting explosion blew the cannon to bits. The whole train carriage was also destroyed, nothing was allowed to fall into enemy hands. A pile of twisted metal and a big wrecked 80cm barrel was all that was left of one of the two guns. Gustav, the other big railway cannon was discovered in pieces in Russia in the same year, she had been blown apart. The famous ' Paris Gun' that shelled Paris in World War I, had a caliber of 'only' 22cm or 8.6 inches but had a fantastic range of 76 miles. Paris Gun at Altenwalde Range. The guns barrel is positioned at 60 degrees. The name Big Bertha was soon attached to any railway gun though, even though 'Big Bertha's' were actually 420mm or 16.5 inch mortars which had a range of 'only' 9 miles. With the end of WWII also saw the end of the big railway cannons, they were not deemed worth the maintenance as I have stipulated throughout this page. Why bother when you can fly a few hundred strategic heavy bombers over the target, do a bit of carpet bombing and yield the same results.