Historical+Engineering question

[Sunforged General]

So lets assume during World War II that France does not fall in 1940 and the western front becomes a stalemated as in WWI. 1941 comes around and the Germans roll out Schwerer Gustav and and decide to use it to try to destroy Gros Ouvrages, the largest forts on the Maginot line, in an attempt to try to break through the Line and end the stalemate.

How effective would Schwerer Gustav be vs the Gros Ouvrages? I know a 800mm siege gun is extremely powerful. But the Gros Ouvrages just so happened to be some of the strongest fortifications ever constructed in human history.

 

[JodelDiplom]

So lets assume during World War II that France does not fall in 1940 and the western front becomes a stalemated as in WWI. 1941 comes around and the Germans roll out Schwerer Gustav and and decide to use it to try to destroy Gros Ouvrages, the largest forts on the Maginot line, in an attempt to try to break through the Line and end the stalemate.

How effective would Schwerer Gustav be vs the Gros Ouvrages? I know a 800mm siege gun is extremely powerful. But the Gros Ouvrages just so happened to be some of the strongest fortifications ever constructed in human history.

Shell any structure long enough with super heavy artillery, and it will suffer.

That being said, I'm not a civil or military engineer

Edit: something like this
https://en.m.wikipedia.org/wiki/Ouvrage_Simserhof
Might have its underground structures withstand bombardment for a long time, but the above ground structures would all be destroyed fairly quickly by targeted super heavy howitzer fire.

If the Germans get a howitzer within range, that is. The fortress has its own heavy artillery after all which probably outranged the German howitzers...

 

[Herbert West]

Siege of Sevastopol, enough said

 

[Sunforged General]

Siege of Sevastopol, enough said

The Soviet forts were not nearly as strong or well built as the Maginot line. France put huge amounts of money and brilliant engineers to build the Maginot Line. The Soviet Union tended to make shoddy products, especially in the 1930s. Also much of the USSR's military spending was focused on offensive weapons, presumably their defensive forts fund was second priority.

 

[JodelDiplom]

The Soviet forts were not nearly as strong or well built as the Maginot line. France put huge amounts of money and brilliant engineers to build the Maginot Line. The Soviet Union tended to make shoddy products, especially in the 1930s. Also much of the USSR's military spending was focused on offensive weapons, presumably their defensive forts fund was second priority.

Citation needed for all those sweeping assumptions.

The Soviets were no slouches when it came to civil engineering. In the 1920s and 1930 they built a humongous number of hydroelectric dams, railway bridges, and factories. They had American engineers come and teach them the best techniques of the time. You can't just throw an assumption around that everything they did was shoddy, that's silly.

 

[Sunforged General]

Citation needed for all those sweeping assumptions.

The Soviets were no slouches when it came to civil engineering. In the 1920s and 1930 they built a humongous number of hydroelectric dams, railway bridges, and factories. They had American engineers come and teach them the best techniques of the time. You can't just throw an assumption around that everything they did was shoddy, that's silly.

https://en.wikipedia.org/wiki/Consumer_goods_in_the_Soviet_Union

"The industry of the Soviet Union was usually divided into two major categories. Group A was "heavy industry," which included all goods that serve as an input required for the production of some other, final good. Group B was "consumer goods" (final goods used for consumption), including food, clothing and shoes, housing, and such heavy-industry products as appliances and fuels that are used by individual consumers. From the early days of the Stalin era, Group A received top priority in economic planning and allocation so as to industrialize the Soviet Union from its previous agricultural economy. "

Yes, Soviet hydroelectric dams were nice and fancy, because they were Group A items, tied to heavy industry, top priority. Fortifications constructed during the 1930s should be group B items, since they were not tied to industry, production, and since Stalinist ideology was focused more on expansion than defense. This is reinforced When the Stalin line was abandoned, and the Molotov-Line was not ready in time for the German invasion due to low priority.

As far as I can tell, none of the forts around Sevastopol were of comparable size to Gros Ouvrages. The sweeping assumption you are making is that Soviet fortifications are of equal quality to French forts, which is unlikely at best.

 

[TheFlemishDuck]

I'm not sure anyone can nessecarily provide you the technical answer. There is no much comparison to this gun in regards to caliber seeing as its still significantly bigger than battleship guns. The best i could find is a comparison with the Tallboy bomb which was a type of seismic bomb. While still lighter, this type of seismic bomb was very effective against fortifications due to it's delayed detonation. This sort of bomb would first puncture the concrete shell (11 foot of reinforced concrete like in Gross ouvrages being no issue) and then explode underneath creating cavity's under the foundations. Tallboy bombs thus would have made short work of it. A shell from the Schwerer Gustav would have been heavier still but usually would typically have had more of it's force direct outwards.
Eitherway, good French bunkers or not, i'd think the dammage when hit directly would be very significant and much less so for not hitting in directly. Concrete can be easily enough blasted with explosives i gather but the way the force of the blast is distrubuted afcourse matter aswel, but then i presume that a shell of the Schwerer gustav due to it's weight and force would first bury itself a bit into the structure before exploding. However it would be hard for the Schwerer Gustav to hit anything directly on purpose i presume.

The germans apparently had bunker buster shells that would have gone trough the concrete armor of French bunkers aswell, see link below, though these shells were not specificly for the Schwerer gustaf.
https://en.wikipedia.org/wiki/Röchling_shell

As far as I can tell, none of the forts around Sevastopol were of comparable size to Gros Ouvrages. The sweeping assumption you are making is that Soviet fortifications are of equal quality to French forts, which is unlikely at best.

But reading up te sources the concrete was as thick i'f not thicker. Why is it a sweeping assumption to make that the protection of Russian forts would be similar to those to French??

http://www.allworldwars.com/The History of Maxim Gorky-I Naval Battery.html

Most fortifications like coastal ones seem to have up to about 11 foot of concrete thickness similar to the Maginot. I guess this standard has a reason, and afaik that's about the thickness that would withstand shells fired from Battleships.

 

[bz249]

Those fortifications are not meant to be impenetrable theater shields capable of withstanding a full bombardment from a squadron Imperial II star destroyers for indefinite time, but border fortifactions which should:
- prevent a sneak attack by a smallish force to capture vital French political/military/transportation targets
- in case of a general war provide a force multiplier for the defense till the mobilization is completed and the French Army come in numbers to the front
- if possible channel the the German attack to the Low Countries
- if possible provide staging ground for a follow-up offensive

 

[JodelDiplom]

The Soviet forts were not nearly as strong or well built as the Maginot line. France put huge amounts of money and brilliant engineers to build the Maginot Line. The Soviet Union tended to make shoddy products, especially in the 1930s. Also much of the USSR's military spending was focused on offensive weapons, presumably their defensive forts fund was second priority.

But reading up te sources the concrete was as thick i'f not thicker. Why is it a sweeping assumption to make that the protection of Russian forts would be similar to those to French??

http://www.allworldwars.com/The History of Maxim Gorky-I Naval Battery.html

Most fortifications like coastal ones seem to have up to about 11 foot of concrete thickness similar to the Maginot. I guess this standard has a reason, and afaik that's about the thickness that would withstand shells fired from Battleships.

https://de.m.wikipedia.org/wiki/Küstenbatterie_Maxim_Gorki_I

Brief description of the Maxim Gorki battery at Sebastopol, one of the lynch pins of the Soviet defense (in German)

4 m of layered concrete, deep tunnels, electricity generators aplenty, state of the art optics for artillery sighting. Resisted the Wehrmacht for a month or so against an arsenal of 600 artillery pieces in 1942.

Doesn't sound like a badly built fort.

 

[Henry IX]

The German super-heavy artillery probably could have destroyed French forts, however, it would most likely have taken multiple shots to do so (ranging shots then several direct hits to disable the forts). Given the firing rate of these guns of less than 2 shots an hour at maximum, any assault would be a highly predicable action. In addition, as Verdun demonstrated in WWI, even ruined forts could provide formidable strongpoints. Given these factors the Germans would be conducting the exact style of positional warfare the French were trained and equipped for.

As bz249 pointed out, forts are not to provide impenetrable defences, but rather to limit and channel the enemies' attacks and to provide force multipliers for the defence and even if demolished by super-heavy artillery, they would still be working to reduce the tempo of German operations and give the French plenty of time to prepare forces for defence in depth and counter-attacking forces in the sector.

 

[Sunforged General]

Those fortifications are not meant to be impenetrable theater shields capable of withstanding a full bombardment from a squadron Imperial II star destroyers for indefinite time, but border fortifactions which should:
- prevent a sneak attack by a smallish force to capture vital French political/military/transportation targets
- in case of a general war provide a force multiplier for the defense till the mobilization is completed and the French Army come in numbers to the front
- if possible channel the the German attack to the Low Countries
- if possible provide staging ground for a follow-up offensive

While all of these are true, the Gros Ouvrages were none the less built to very high specifications for resisting bombardment. Ouvrage Schoenenbourg for example:

"On 19 June 1940, German Stukas attacked Schoenenbourg and other ouvrages, returning on the 20th and 21st. The attacks on the 21st were joined by a bombardment with 420 mm siege mortars, lasting three days."

"Schoenenbourg fired during this period in support of nearby casemates, not seriously affected by the bombardments."

"The inventory of German ordnance fired against Schoenenbourg was assessed after the armistice, and found to comprise 160 aerial bombs, 50 42 cm shells, 33 28 cm shells, and approximately 3000 smaller projectiles,[22] the most ammunition used against any fortification in France."

 

[Sunforged General]

https://de.m.wikipedia.org/wiki/Küstenbatterie_Maxim_Gorki_I

Brief description of the Maxim Gorki battery at Sebastopol, one of the lynch pins of the Soviet defense (in German)

4 m of layered concrete, deep tunnels, electricity generators aplenty, state of the art optics for artillery sighting. Resisted the Wehrmacht for a month or so against an arsenal of 600 artillery pieces in 1942.

Doesn't sound like a badly built fort.

That begs the question, how thick were the walls of the Gros Ouvrages and how deep were they buried. While the Casemates above ground usually had 8.2 ft reinforced concrete walls and the front was covered by large mounds of earth or gravel, I've not been able to find how thick the walls of the actual ouvrage was. I could have sworn somewhere I read that some Ouvrages were as deep as 80ft underground+10 ft thick reinforced concrete walls. But I cant seem to find it again.

So if the Ouvrage containing vital systems is 80 ft underground Schwerer Gustav might not even be able to affect it, meanwhile the casemates above ground were probably small enough that hitting them directly would be very difficult for such a long range weapon. And the walls of the casemates at 8.2ft thick were probably thick enough to withstand indirect hits.

 

[TheFlemishDuck]

That begs the question, how thick were the walls of the Gros Ouvrages and how deep were they buried. While the Casemates above ground usually had 8.2 ft reinforced concrete walls and the front was covered by large mounds of earth or gravel, I've not been able to find how thick the walls of the actual ouvrage was. I could have sworn somewhere I read that some Ouvrages were as deep as 80ft underground+10 ft thick reinforced concrete walls. But I cant seem to find it again.

The tables if found so far doesn't make the maginot anything special in regards to supposedly superthick structure. The walls and roofs apparently had a level of protection that was rather standard for the time and then typicly rated to protect from various different calibers of weapons. Most data and tables i can find back about fortifications show roughly the same specifications and again i think that makes sense.

Take in mind that the Maginot comprised of a multitude of large forts with the addition of many more smaller forts. Take also in mind the overal philosophy of fortifications as explained by bz249 and the need of the French to keep the cost of the maginot relativly low as to not make it cost ineffective in comparison to adding more equipment to their army's. There was no incentive for the French to throw so much resources at the Maginot as to make forts that were more protected as usual, just having a large amount of the standard type of fort that would pose an issue to any army would be fine. And while the Maginot might look impressive with for example all it's underground infrastructure it was nothing special i think.

So if the Ouvrage containing vital systems is 80 ft underground Schwerer Gustav might not even be able to affect it,

Thats less of an issue as long as you can disable the firepower that emits from such forts. And afaik it's not like you had to penetrate the protection of the fort to nessecarily disable its guns as various random dammage might block te guns or affect the crews.

And the walls of the casemates at 8.2ft thick were probably thick enough to withstand indirect hits.

depends how close they might land i guess. Eitherway, at a rate of fire of 2 shots per hour Schewer Gustaf is more the icing on the cake of a heavy bombardment than something you could solely rely on. Then again, even if Scherer Gustaf would have missed likely it would deal plenty of damage anyhow if there were troops around that fort that were siting in the open, which might be likely when reinforced.

 

[Sunforged General]

The tables if found so far doesn't make the maginot anything special in regards to supposedly superthick structure. The walls and roofs apparently had a level of protection that was rather standard for the time and then typicly rated to protect from various different calibers of weapons. Most data and tables i can find back about fortifications show roughly the same specifications and again i think that makes sense.

Take in mind that the Maginot comprised of a multitude of large forts with the addition of many more smaller forts. Take also in mind the overal philosophy of fortifications as explained by bz249 and the need of the French to keep the cost of the maginot relativly low as to not make it cost ineffective in comparison to adding more equipment to their army's. There was no incentive for the French to throw so much resources at the Maginot as to make forts that were more protected as usual, just having a large amount of the standard type of fort that would pose an issue to any army would be fine. And while the Maginot might look impressive with for example all it's underground infrastructure it was nothing special i think.



Thats less of an issue as long as you can disabe the firepower that emits from such forts.

Thats fair, good chart, but the underground infrastructure is precisely what made the Maginot Line special. The Czech border fortifications for example were, for the most part, not interconnected via underground tunnels and supply depots from what I understand. Same for the Stalin line, Siegfried line and Mannerheim line. There was no interconnected web of underground supply lines for those defenses comparable to the Maginot Line.

 

[TheFlemishDuck]

Thats fair, good chart, but the underground infrastructure is precisely what made the Maginot Line special. The Czech border fortifications for example were, for the most part, not interconnected via underground tunnels and supply depots from what I understand. Same for the Stalin line, Siegfried line and Mannerheim line. There was no interconnected web of underground supply lines for those defenses comparable to the Maginot Line.

from wiki:
Gustav was later deployed in the Soviet Union during the Battle of Sevastopol, part of Operation Barbarossa, where, among other things, it destroyed a munitions depot located roughly 30 m (98 ft) below ground level.

https://en.wikipedia.org/wiki/Schwerer_Gustav

It's perhaps questionable how usefull it is to interconnect forts, from what i can read from the fort of Eben Emael it's considered as a potential detriment because the lines are so long that it would be hard to effeciently react to the situation on the ground.

 

[Sunforged General]

from wiki:
Gustav was later deployed in the Soviet Union during the Battle of Sevastopol, part of Operation Barbarossa, where, among other things, it destroyed a munitions depot located roughly 30 m (98 ft) below ground level.

https://en.wikipedia.org/wiki/Schwerer_Gustav

Yes the fortifications around Sevastopol are somewhat unique, and also not a part of the Stalin line. The fortifications around Sevastopol were built with withstanding battleship fire in mind. Also that munitions depot was 30m below the sea, not solid ground, but none the less, still a impressive feat.

 

[TheFlemishDuck]

Yes the fortifications around Sevastopol are rather unique, and also not a part of the Stalin line. The fortifications around Sevastopol were built with withstanding battleship fire in mind. Also that munitions depot was 30m below the sea, not solid ground, but none the less, still a impressive feat.

Well i think it sufficiently answers youre question as Sevastopol had similar protection to a gross ouvrage and Schwerer Gustaf managed to hit one of it's ammunition depots deep underground.

 

[Sunforged General]

Well i think it sufficiently answers youre question as Sevastopol had similar protection to a gross ouvrage and Schwerer Gustaf managed to hit one of it's ammunition depots deep underground.

I'm not an engineer, but I think 25m of solid earth would offer more protection than 30m of water. If they used a high explosive, it probably didnt even detonate until it hit the concrete.

 

[TheFlemishDuck]

I'm not an engineer, but I think 25m of solid earth would offer more protection than 30m of water. If they used a high explosive, it probably didnt even detonate until it hit the concrete.

I dunno if 25m of earth would offer more protection than 30m of water, i presume a Schwerer Gustaf shell would plow trough both as if it was butter. In fact afaik water is far harder to compress than earth and would distrbute its upward pressure better therefore actually likely offers more resistance especially the deeper the projectile goes. But if i read correctly that ammunition magazine also had 10 meters of concrete protection. I guess the 10 meters was also there to resist the pressure of the water. Also i read somewhere else that a Schwerer gustav shell would detonate 30m underground on average anyway, not unsurprising for a shell of that size and velocity i guess. Not to hard to see when looking at the kind of craters it left behind neither:

fig 1a: Germans and their rediculous guns omfg

Wiki gives an overview of it's performance around Sevastopol:

The siege of Sevastopol was the gun's first combat test. 4,000 men and five weeks were needed to get the gun in firing position; 500 men were needed to fire it.[7] Installation began in early May, and by the 5th of June the gun was ready to fire.[8] The following targets were engaged:

• 5 June
  • Coastal guns at a range of 25,000 m. Eight shells fired.
  • Fort Stalin. Six shells fired.
• 6 June
  • Fort Molotov. Seven shells fired.
  • "White Cliff" also known as "Ammunition Mountain": an undersea ammunition magazine in Severnaya ("Northern") Bay. The magazine was sited 30 metres under the sea with at least 10 metres of concrete protection. After nine shells were fired, the magazine was ruined and one of the boats in the bay sunk.[9]
• 7 June
  • Firing in support of an infantry attack on Südwestspitze, an outlying fortification. Seven shells fired.
• 11 June
  • Fort Siberia knocked out of action. Five shells fired.
• 17 June
  • Maxim Gorky Fortresses bombarded. Maxim Gorky 1 knocked out of action, Maxim Gorky 2 damaged. Five shells fired.

Ultimatly Schwerer Gustav was designed to deal with the Maginot, i believe the Germans just went to specifications that would "surely make it effective". You would think that it would be a pretty stupid effort to design and build such a gun if it would also prove to be ineffective besides the stupendous amount of prepperation and resources needed to even put it in action.

 

[Sunforged General]

I dunno if 25m of earth would offer more protection than 30m of water, i presume a Schwerer Gustaf shell would plow trough both as if it was butter. In fact afaik water is far harder to compress than earth and would distrbute its upward pressure better therefore actually likely offers more resistance especially the deeper the projectile goes. But if i read correctly that ammunition magazine also had 10 meters of concrete protection. I guess the 10 meters was also there to resist the pressure of the water. Also i read somewhere else that a Schwerer gustav shell would detonate 30m underground on average anyway, not unsurprising for a shell of that size and velocity i guess. Not to hard to see when looking at the kind of craters it left behind neither:

fig 1a: Germans and their rediculous guns omfg

Wiki gives an overview of it's performance around Sevastopol:

The siege of Sevastopol was the gun's first combat test. 4,000 men and five weeks were needed to get the gun in firing position; 500 men were needed to fire it.[7] Installation began in early May, and by the 5th of June the gun was ready to fire.[8] The following targets were engaged:

• 5 June
  • Coastal guns at a range of 25,000 m. Eight shells fired.
  • Fort Stalin. Six shells fired.
• 6 June
  • Fort Molotov. Seven shells fired.
  • "White Cliff" also known as "Ammunition Mountain": an undersea ammunition magazine in Severnaya ("Northern") Bay. The magazine was sited 30 metres under the sea with at least 10 metres of concrete protection. After nine shells were fired, the magazine was ruined and one of the boats in the bay sunk.[9]
• 7 June
  • Firing in support of an infantry attack on Südwestspitze, an outlying fortification. Seven shells fired.
• 11 June
  • Fort Siberia knocked out of action. Five shells fired.
• 17 June
  • Maxim Gorky Fortresses bombarded. Maxim Gorky 1 knocked out of action, Maxim Gorky 2 damaged. Five shells fired.

Ultimatly Schwerer Gustav was designed to deal with the Maginot, i believe the Germans just went to specifications that would "surely make it effective". You would think that it would be a pretty stupid effort to design and build such a gun if it would also prove to be ineffective besides the stupendous amount of prepperation and resources needed to even put it to bear.

Well, I find it troubling that Schwerer Gustav somehow penetrated 10m of concrete when its maximum specified penetration was 7m of concrete or 1m of steel plate. And this was supposed to be at the highest elevation the gun barrel could be raised. This is on the same wiki page. https://en.wikipedia.org/wiki/Schwerer_Gustav#Ammunition

Either the Soviet fortification wasn't really 10m of concrete, or it was shoddy construction, or They somehow improved the gun to be more powerful than it was originally designed to be.