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HOI4 Dev Diary - Railway guns never tire

Hello there, C0RAX again.

It’s time again to reveal some more secret information that was hinted at in the last dev diary. Specifically this week will be revolving around the final part of railways and trains. So without any more need for introduction here are our stars of the show today.

The railway guns.

So to start off I'll go through how you get a railway gun on the map because it’s a little different to normal land units. First of all you are going to want to research railway guns which comes after armoured trains.
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Then you can find it in your production tab just like building normal equipment. But unlike other equipment you build, these production lines are limited to 5 factories and the railway gun won't be added to your stockpile.
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Instead, once completed, your brand new railway gun will appear in your capital, in this way they are built similar to capital ships.
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Moving your railway gun is limited to provinces with railways, and so to get to the front you must have a rail connection. Taking into account the rail conversion time when capturing territory is important as you will have to wait for the big guns to be able to help you out.
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You can also attach railway guns to armies just like with planes and they will attempt to place themselves relative to the frontline. If you have several, they will be distributed where possible to support your army. There is also a quick select button on the army to select all railways guns attached to an army should you need to.
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Finally, the last bit of control understanding is range. Railway guns have a range in which they can support and so from any one point are limited in which provinces they can support. This range is shown by hovering over the unit icon.
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On to combat now, here we can see a combat with a supporting railway gun, we have added the useful icon on the combat progress indicator that there is a supporting bombardment. This new icon will also show if there is shore bombardment happening in the combat.
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The combat effects of railway gun bombardment work just like shore bombardment, causing negative combat stat modifiers to those on the receiving end of the big guns. These modifiers affect both soft and hard attack as well as defense values. Notably, these effects do not stack - it becomes more important to spread out your railway artillery than to concentrate it.
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Finally we need to talk about capture and damage, railway guns can be captured via encircling them and damaged by damaging the railway they are placed upon.

Now railway guns are the biggest guns by far used on land and so it's important that we have representations of those built by the major powers. So now we look at the unique guns for the major powers.

This is the German Schwerer Gustav model you will see when playing as the Germans. It's perhaps the most famous railway gun and definitely the biggest and so had to have a part in this feature.
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This is the BL 9.2inch railway gun, a relic of the first world war but these big guns were kept in service until 1945.
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Following that we have the French Canon de 305 another veteran of the first world war.
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Next up is the USA’s 8-inch Mk. VI which remarkably first entered service as late as 1941!
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Type 90 240 mm railway gun whose claim to fame is being destroyed by the retreating Japanese in the soviet invasion manchuria.
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And finally the TM-3-12, three of these were made in 1938 and were used in the winter war against finland, unbelievably these where in service until 1999 (a whopping 61 years of service)
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Finally here's a cool clip of the Schwerer Gustav firing in game.
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Railway guns should not to be produced using the mass production system(like guns, plans, tanks).

Especiallly the Gustav gun for germany could be only produced over a decision like spending as example: 3 civilian + 3 military factories for 720 days to produce 1 gustav gun ( x iron, y chrome + around 5000 manpower + z political power ) or something like that.

Best it would be if each major nagions would have these decisions.

I really dont see any need to mass produce these guns like T-34 (for most nations that would be impossible, for germany,too)

But i like the idea of railway guns
 
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Railway guns should not to be produced using the mass production system(like guns, plans, tanks).

Especiallly the Gustav gun for germany could be only produced over a decision like spending as example: 3 civilian + 3 military factories for 720 days to produce 1 gustav gun ( x iron, y chrome + around 5000 manpower + z political power ) or something like that.

Best it would be if each major nagions would have these decisions.

I really dont see any need to mass produce these guns like T-34 (for most nations that would be impossible, for germany,too)

But i like the idea of railway guns
Germany had 2 but only used 1, they were pretty useless.
 
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useless

but very very expensive and of course if a player like to produce them...why not?

The drawbacks should be high.

The hoi4 ingame effect of these guns should be minimum (but iam not able to discuss the stats, ive to less experience in hoi4 for that)
 
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They should not give bonuses to forts because railway guns are too inaccurate.
You should inform ww2 generals about this revelation. Massive artillery like railway guns were constructed and used specifically to defeat fortified positions. And they were used in this role.

What I find strange is that all railway guns are thrown into one box. Almost all railway guns were 190-250mm and there were a lot of those, while super gun pieces like Gustav were super rare. Yet, in game 600mm Gustav is the same unit as 200mm US, 240mm Japanese, 230mm UK or slightly larger 305mm French or Soviet guns.
 
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Why can RWG not be used to assist a naval invasion combat in range?
They can. They just need to be in range.

What I meant is that they aren't shipped as a part of a naval invasion.

If you invade a port and there's a friendly RWG on land in range of said port they will indeed provide support.

But an RWG in a convoy won't provide support.
 
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Railway guns should not to be produced using the mass production system(like guns, plans, tanks).

As per the DD, it sounds like they're produced more like ships than normal land or air equipment - and compared with larger ships, even the likes of Gustav are still tiddlers. Note on the screenshot in the DD it's possible to set how many you want to produce like ships as well - so someone can decide to just build one, and it'll build and not keep going (assuming I've understood the UI element appropriately - this is a guess - there is a slight chance it could stand for "how many pineapples can fit into the breech").


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They should not give bonuses to forts because railway guns are too inaccurate.

Naval artillery (which, more or less, is what most railway guns were, although I can't speak for the howitzer-types) could be very accurate - I can dig up the distribution of where shells would land after travelling 20-30km if you'd like (going from my ever-unreliable memory, but generally within 200-300m, iirc - a 750m distribution would be seen as very inaccurate - the 14in on the KGVs on the other hand were very accurate over distance) :). Given forts were static targets, they'd be the best kind of targets to fire against, as it's really just a matter of statistics as to how many hits you'd get from how many shots, depending on the size of the target, and the distribution of where shots landed (I'm messing the terminology up terribly here - apologies to people that are all over MPIs and similar).

If you invade a port and there's a friendly RWG on land in range of said port they will indeed provide support.

But an RWG in a convoy won't provide support.

This sounds perfect :)
 
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I have been thinking about this:
"railway guns can be captured via encircling them"
Does it really make sense that they are so easily captured? Reading the wiki entry of the German guns it seems most of the guns were destroyed by their crews before they could be captured. At the very least captured guns should be damaged and require extensive repairs
 
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I have been thinking about this:
"railway guns can be captured via encircling them"
Does it really make sense that they are so easily captured? Reading the wiki entry of the German guns it seems most of the guns were destroyed by their crews before they could be captured. At the very least captured guns should be damaged and require extensive repairs

The Finns for instance captured ten railway guns during the Continuation War: seven TM-1-180s (Finnish designation 180/57 NRaut) and three TM-3-12s (305/52 ORaut). Out of these, five TM-1-180s were repaired before the end of the war and four saw combat use. All three TB-3-12s were repaired but none saw combat use. This despite the Russians making thorough efforts to destroy their railway guns to prevent capture and enemy use. More information here: https://www.jaegerplatoon.net/RAILWAY_GUNS.htm

I've also attached an English summary from Ove Enqvist's Rautatietykistö Suomessa: Unohdettu osa rannikkopuolustusta (Railway artillery in Finland: A forgotten part of coastal defence):

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Why can RWG not be used to assist a naval invasion combat in range?
That isn't what he said.
1) They can't participate in the invasion (i.e., they don't fight their way to shore with the marines).
2) IF they are in range of the combat, they will provide support (just like any other combat they are in range of).

The problem becomes that there are going to be very few locations where you can park a Railway Gun that is in range of the beach you are assaulting. Most likely only the Cross-Channel D-Day/Sea Lion. Most 1 or 2 province islands, or even island chains, are not going to have rail (and I doubt you can put a rail line in a single province) so most likely the South Pacific would be out.
 
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Naval artillery (which, more or less, is what most railway guns were, although I can't speak for the howitzer-types) could be very accurate - I can dig up the distribution of where shells would land after travelling 20-30km if you'd like (going from my ever-unreliable memory, but generally within 200-300m, iirc - a 750m distribution would be seen as very inaccurate - the 14in on the KGVs on the other hand were very accurate over distance) :). Given forts were static targets, they'd be the best kind of targets to fire against, as it's really just a matter of statistics as to how many hits you'd get from how many shots, depending on the size of the target, and the distribution of where shots landed (I'm messing the terminology up terribly here - apologies to people that are all over MPIs and similar).
Most importantly, that Naval Artillery is firing at a moving (not static) target, while it itself is moving. Neither condition would apply to the same naval artillery (almost all of the 'normal' Railway Guns were repurposed Naval Guns, the only ones that I can think of that weren't were the German Heavies) mounted on a railway car.
 
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Most importantly, that Naval Artillery is firing at a moving (not static) target, while it itself is moving. Neither condition would apply to the same naval artillery (almost all of the 'normal' Railway Guns were repurposed Naval Guns, the only ones that I can think of that weren't were the German Heavies) mounted on a railway car.

Aye, absolutely - the figures I referenced above are just the dispersion figures for a static gun fired at a gun testing range on land (as best I can recall from a fairly recent Warship International article - I can look it up for exact figures, but didn't think the detail was necessary), and don't take into account the complexities of target prediction and what-have-you - but the fact that ship-mounted large-calibre naval artillery could hit other ships 20km away while both vessels were maneuvering (and not in parallel) should give some indication of the potential of long-range gunnery if both targets were stationary.
 
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How do I move these across seas? Do they move like any other unit, or is there a special way to do it?
Port to Port (just like any other land unit) probably with the added proviso that both ports must have railroad links.
 
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You should inform ww2 generals about this revelation. Massive artillery like railway guns were constructed and used specifically to defeat fortified positions. And they were used in this role.

What I find strange is that all railway guns are thrown into one box. Almost all railway guns were 190-250mm and there were a lot of those, while super gun pieces like Gustav were super rare. Yet, in game 600mm Gustav is the same unit as 200mm US, 240mm Japanese, 230mm UK or slightly larger 305mm French or Soviet guns.
They knew that, if I remember correctly only germany built them and they only built 2 and used 1 a couple of times. They were used during ww1 and a few times during ww2.
 
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Naval artillery (which, more or less, is what most railway guns were, although I can't speak for the howitzer-types) could be very accurate - I can dig up the distribution of where shells would land after travelling 20-30km if you'd like (going from my ever-unreliable memory, but generally within 200-300m, iirc - a 750m distribution would be seen as very inaccurate - the 14in on the KGVs on the other hand were very accurate over distance) :). Given forts were static targets, they'd be the best kind of targets to fire against, as it's really just a matter of statistics as to how many hits you'd get from how many shots, depending on the size of the target, and the distribution of where shots landed (I'm messing the terminology up terribly here - apologies to people that are all over MPIs and similar).
German generals didn't use them against forts because the guns were too inaccurate the dispersion was 60m-740m. It was only used at Sevastopol.
 
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German generals didn't use them against forts because the guns were too inaccurate the dispersion was 60m-740m. It was only used at Sevastopol.

I'm just going from Wiki (ie, apologies for any inaccuracies due to this) - but it looks like Gustav wasn't ready in time for the Battle of France, so while it was only used at Sevastopol, there weren't many situations (heavily fortified positions that took a long time to defeat) that it was tactically appropriate for (particularly given the long time it took to set up - I suspect more 'normal' calibre railway guns were more flexible tactically). At least from the Wiki article, the impression (and its just a general impression) given is that its impact on the fortifications was pretty decent, relative to rounds fired. Dora was brought to Stalingrad, but (assuming the wiki is correct....) by the time it got the Soviets were starting to turn things around, and they pulled it back. The impression given is that they were very much intended for use against fortified positions, and had been intended for further use had Germany not been put on the defensive.


By the look of it (and it's just a brief look), most railway guns, German or otherwise, were smaller and often based around naval artillery designs. Gustav's just the one that sticks in the mind, because it was a big 'un!
 
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