Much as that thing weighs, I think it would bog down in dry fields. Very slow also. By the time it go to where it was going the war would be over. Albert Speer cancelled them anyway.

If the cannon could swivel only a few degrees to either side it would be enough. This gun fired on ships in the Canal and as you know they can't turn on a dime.

Interesting was that the nazis wanted a Self-Propelled Howitzer with the 800mm cannon: The 'Landkreuzer' (Land Cruiser) P.1500 Monster. Can you image that, rolling through the muddy fields in Russia :D

http://en.wikipedia.org/wiki/Landkreuzer_P._1500_Monster
and check this one; with 2x 280mm
http://en.wikipedia.org/wiki/Landkreuzer_P._1000_Ratte

Another monster! I see this one pivots front and rear. If the tracks were ended in a 'Y' fashion then it could hit almost any target.

Yes, Gustav and Dora were used against mother Russia. The one I saw was Leopold, a K5 280mm railway gun. Apparently they did fire upon British ships. I saw this gun 20 years ago when I was a little dude ;)

I saw some old war movies with these things blasting away and was always fascinated be the sheer power of them. I looked this one up on wikipedia. I didn't see that it could train (right and left) which would mean it was limited because it had to shoot straight ahead. The recoil is impressive and took 30 to 45 min to load.(maximum of 14 shots per day). Never was used against France but was against Russia.

The largest coastal cannon I saw was in Nord-Pas de Calais, Audinghen, France (closest part to the UK). Only a 280mm rail gun but still very impressive.

http://en.tracesofwar.com/artikel/715/Mus%E9e-du-Mur-de-LAtlantique-Batterie-Todt.htm

heavy shit

800mm shell up close

the tiny shell could weigh between 4800 and 7100 kg!