In World War II the Germans made use of huge railway cannons, Dora and her brother Gustav were the biggest.

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.

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In 1937 Hitler wanted a huge cannon that could destroy enemy targets such as fortresses at long range. The criteria that was required was that the shell had to penetrate 7 meters of steel reinforced concrete or at least 1 meter of hardened armour plate. The range required was to be over 25 miles.

The Maginot line was also considered to be a worthy target.

Hitler initially ordered three such guns to be built.

Krupp steel industries was given the job of creating these huge guns and Professor Erich Muller worked out the mathematics of producing them. He arrived at a calibre of 80cm 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.

At the beginning of January 1942 the gun was ready. 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 low gear to be able to move the carriage an inch forward at a time.

Dora was loaded slowly with huge winches and electrically powered rams by a crew of 250.

The initial target was  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 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 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 destroyed. One of the shots missed the target and sunk a ship in the harbour.

Seven shots were fired the next day in the same vicinity at nothing in particular !

The gun was again used to more worth some days later when Fort Siberia was hit with five shots and destroyed as was Fort Maxim Gorki.

The barrel of the gun was worn out and Gustav had to be dis-mantled and shipped back to Germany to be re-fitted with a new barrel, this took weeks and weeks to do costing effort time and money and Germanys resources at this time was extremely pushed as it was.

Dora was only fired several times more and had to be taken apart, transported and re-assembled for every new target in different parts of enemy territory and the railway tracks had to be made for it each time.

What a waste of time, money, manpower and over all resources just for a few shots at the enemy.

The total accomplishment of these guns was in respect quite small.

One gun was destroyed with explosives in 1945 near Metzenhof, Bavaria by its crew as the allies were advancing.

Paris Gun at Altenwalde Range.  The guns barrel is positioned at 60 degrees. 

'Big Bertha's' were actually 420mm  or 16.5  inch mortars which had a range of  'only' 9 miles.