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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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Cheers for the DD C0RAX, and the extra info Arheo and Cranium Muppet :) Finally land warfare gets at least a small fraction of the style and panache of naval combat :cool: The implementations sounds great - lots to love. The only question I'd have in relation to railway guns is whether there was any consideration of making them help wear down forts a bit easier (so perhaps have a small reduction on the fort malus for attackers) - note, I'm not sure if this is a good idea, just mentioning in case useful.

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.

This is super-cool :) Would there be any scope to allow this for ships, perhaps by ship type as a simplification? Most of those railway guns (with some key exceptions) are relatively lightweight compared with naval artillery, and yet naval artillery is perhaps a bit more limited than it was historically (noting that any range for naval artillery shouldn't be at the shore, but taken from some distance offshore). Also a good argument for allowing the construction of monitors (not used a lot historically, but if frontlines in Europe had bogged down and there weren't enough BBs to go around they may well have got more use).

This new icon will also show if there is shore bombardment happening in the combat.

Very nice :)

Finally here's a cool clip of the Schwerer Gustav firing in game.

Lots of action going on in that screenshot - very cool.

Railway artillery is big.

Well, when you're talking in terms of land warfare at least :p After the railway gun, the largest piece of equipment in land warfare is something like a 190-ton tank - in naval terms that's the weight of just one of the four twin turrets on a County Class cruiser. Gustav was heavier - about the weight of a standard interwar British/American destroyer, or a bit less than the weight of one of the Littorio's three triple turrets. In terms of industrial cost, benchmarking to these might help with consistency (which the 5 MIC and resource cost may do already, I'm a bit tired to crunch the numbers this evening).

For a naval-themed pic for a DD that mentions shore bombardment, it's a bit easy - and I wouldn't want to take attention away from railway guns that, did, after all, often use barrels originally designed or made for naval artillery. So in the spirit of today's DD, here's a pic of a model of HMG (His Majesty's Gun) Gladiator, that was used to fire over the Channel at Calais, as well as at German coastal convoys passing through - it used a 13.5in Mk V gun originally designed for (and probably used, but I don't have any books on railway guns, so that's a guess) in WW1-era battleships (that were all scrapped after the Washington Treaty).

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For a naval-themed pic for a DD that mentions shore bombardment, it's a bit easy - and I wouldn't want to take attention away from railway guns that, did, after all, often use barrels originally designed or made for naval artillery. So in the spirit of today's DD, here's a pic of a model of HMG (His Majesty's Gun) Gladiator, that was used to fire over the Channel at Calais, as well as at German coastal convoys passing through - it used a 13.5in Mk V gun originally designed for (and probably used, but I don't have any books on railway guns, so that's a guess) in WW1-era battleships (that were all scrapped after the Washington Treaty).
Good picture, and one that brings up a couple comments and a couple questions:

All the major powers had this technology by the end of the Great War, and most (that had not been disarmed by treaty) had multiple examples rattling around that could be, and were, quickly activated when global war again became a thing. Also, all the major powers had obsolete or spare naval and coastal defense guns, which could be (and were) repurposed as railway guns. Are the powers that already had such things, going to be required to reinvent the wheel, and then rebuild it?
 
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Will it be possible to transport railway guns over sea? Idk how realistic it would be irl
If you search dev responses, you'll find this at post #45:
It is pretty much hardcoded for RGs. They can, however, be navally transported if you want to bring some on your invasion holidays.
 
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i appreciate it prdx this weapon system finally enters the game, as well as having done research about other nations variants.
HOI4 coming to an end, it will be exciting in a HOI5 where more geographical detail as such the stats of the weapons sytem will actually be translated better to impact the effect.
Also where I longly wait for is that HOI5 will better reflect slight manpower changes eg. when frontlines exist and small skirmishes happen between recon units etc.
I do enjoyed playing hoi4 but the absence of realistic manpower reserves as well as mp not realistic when overtaking teritorry has stopped me from playing the game. Nevertheless, i will play it probably this year one more time as japan, to see how i can breakthrough at beijng now without cheesy tactics now deploying this system.
 
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Good picture, and one that brings up a couple comments and a couple questions:

All the major powers had this technology by the end of the Great War, and most (that had not been disarmed by treaty) had multiple examples rattling around that could be, and were, quickly activated when global war again became a thing. Also, all the major powers had obsolete or spare naval and coastal defense guns, which could be (and were) repurposed as railway guns. Are the powers that already had such things, going to be required to reinvent the wheel, and then rebuild it?

That's a very good point - depending on stocks on-hand in 1936, there may be good argument to start majors who already had railway guns with a railway gun or two. Similarly, perhaps having some kind of decision for naval powers with surplus barrels (mainly UK/US iirc) to be able to make a railway gun or two on the cheap by putting a partially-completed one into production (the gun likely to be by far the most expensive and industrially-intensive part of the unit).

There were further developments in railway guns - it's not something I'm into specifically (I've just picked up on bits and pieces inasmuch as they relate to modifications to existing naval artillery) but the British, for example, relined an old BB gun (maybe 13.5 in?) to 8in to create a very-high-velocity gun, which I think was railway-mounted.

Will it be possible to transport railway guns over sea? Idk how realistic it would be irl

It was absolutely possible to transfer the guns themselves over the sea (Britain imported (from the US) naval artillery up to 14in calibre in size during WW1) - I would expect it to be very feasible to take the gun off the carriage, load both on a merchant ship (perhaps the carriage in two parts, depending on its size), and then reassemble at the other end. For very large guns like Gustav, I would expect a process like this to still be possible (the gun might have to be broken down into its components - eg, barrel and breech transported separately, if that was possible - not being repurposed naval artillery I don't know the details on Gustav), albeit more difficult.
 
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Personally I view how it works more being about the effect of having them around more then what they actually do. If you think about how big slow fireing guns would be used, they wouldn't be used to destroy x platoon or even company they'd be used primarily to attack command centres and supply dumps or big concentrations of units or fortifications, their targetting is more hours/days then minutes after all. As a result there are two ways it can impact combat as far as I can see, firstly directly by blowing up things (probably things that are stationary for long periods and are large as above) and by acting as a threat and preventing things. Imagine if you are the commander of a division and your enemy has a railway gun, you want to keep moving your HQ around to prevent it being located and struck (and so time that would otherwise be spent planning is spent moving, you have to rely more on radio and runners which are more fragile/insecure then hardlines, your unit may not always know where to find you and so will hesitate without orders, etc), you can't have big supply dumps or artillery parks so have to spread these things out (resulting in ineffiency and confusion with the tech of the day), you can't concentrate your forces so much as again it gives a juicy target, bridges/roads/rail could be hit maybe not in ways that prevent its use but slow things down, the big fort you planned to anchor your lines might be battered flat better spread out more/rely on it less, etc. All of this is without fireing a shot, just from the potential damage the gun could do and I think in reality these kinds of weapon are more about the potential threat then the actual damage they do. To my mind this seems to fit how it works in game.

For people saying they think that there should be different types of railway guns personally I think that is added complexity without added benefit for the majority of players. Hearts of Iron is very much a broad strokes kind of game and even then is really intimidating for the majority of new people. By legal and to an extent moral necessity it is unable to touch on things that were the huge issues during this period of history and really I can't see how it could or should without either being the most depressing game ever or becoming a game which attracts the worst people. Basically I think that guns are either being used more strategically at a higher level for long range long duration fort busting/disruption fire as rail guns were used or they are adequately represented by artillery within units. I think like how you have AA/AT/ART as a nebulous "does a unit of equipment represent one medium gun, several small guns or part of a big gun" you can also have the same with railway guns, i.e. "does a unit of railway gun represent a single slow fireing huge gun, a single medium gun fireing more rapidly or several smaller guns operating together".

For the question of whether the Gustav was the right thing to use for the German model its probably that it was used as its more recognizable by the general player then most guns and if they hadn't you know there would be an equal number of complaints about why didn't they use it.

For the strategic element, when has strategic bombardment by railway guns done anything significant, thousands of bombers dropping tonnes of bombs on cities barely did anything for most of the war what will one 12 inch gun do? Railway guns are of operational significance more then anything.

Sorry for the rant I just get annoyed with everything always being doom and gloom and "HOI5 when?" when I get on here these days, also sorry for any spelling errors I've tried to correct/reword anything that looked janky but might have missed some.
 
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Probably building wonder weapons would have actually saved lives over regular equipment and ended the war even faster since they would have been practically useless in most cases. Germany committing resources to crazy shit means fewer tigers, stugs,and stukas.
That's what I said. Only if the butchers at the top made that shitty waste of resources fewer people would have died.
 
by acting as a threat and preventing things. Imagine if you are the commander of a division and your enemy has a railway gun, you want to keep moving your HQ around to prevent it being located and struck (and so time that would otherwise be spent planning is spent moving, you have to rely more on radio and runners which are more fragile/insecure then hardlines, your unit may not always know where to find you and so will hesitate without orders, etc), you can't have big supply dumps or artillery parks so have to spread these things out (resulting in ineffiency and confusion with the tech of the day), you can't concentrate your forces so much as again it gives a juicy target, bridges/roads/rail could be hit maybe not in ways that prevent its use but slow things down, the big fort you planned to anchor your lines might be battered flat better spread out more/rely on it less, etc. All of this is without fireing a shot, just from the potential damage the gun could do and I think in reality these kinds of weapon are more about the potential threat then the actual damage they do. To my mind this seems to fit how it works in game.
agree with everything you've mentioned except this "indirect effect". Correct me if I'm wrong, but there was never to my knowledge a single instance where the presence of a railway gun causing such problems of organization and deployment for the enemy. most of the time they were treated like any other artillery fire the enemy may have. If anything, attacking a rail gun position would probably be easier since you can't manoeuvre them nor quickly retreat. Because of that limitation, their design and use since WW1 were always against big static targets, like fortifications, and not even targeting headquarters or things like that because usually the enemy didn't even know where they are, and when they did, it was far easier and more efficient to call the divisional artillery and air support. You also need to keep in mind their rather large margin or error compared to the smaller artillery which prevented them from being effective in actual combat.
At any rate, making railway guns contribute directly to combat and with no anti-fortification role flyes directly in the face of what they were even made for.
 
A little disappointing that there's only one railway cannon, and that it's just land-based CAS.
Anyway, how moddable is the rail equipment going to be?
For example, can someone make armored trains act as battlefield support the same way that the railway guns do? And how about the normal trains, how exactly do they work? Are they just land convoys or is there enough substance there for modders to add a larger research tree to it?
 
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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.
So the cap is 25% with 15% per gun? or just 15%? (will cap be listed in tooltips/description/army modifiers, btw?) which gets further reduced when supporting multiple combats, right?
What about Shore Bombardment? Since it's listed as a different modifier do these two stack?
 
What about armored trains? I see a lot of info about the behemoths (railway guns) but what combat capabilities would ordinary armored trains have and how would they work?
 
What about armored trains? I see a lot of info about the behemoths (railway guns) but what combat capabilities would ordinary armored trains have and how would they work?
Armored trains were explained in a previous dev diary.
 
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So the cap is 25% with 15% per gun? or just 15%? (will cap be listed in tooltips/description/army modifiers, btw?) which gets further reduced when supporting multiple combats, right?
What about Shore Bombardment? Since it's listed as a different modifier do these two stack?
Cap is 15% (unless it's gets rebalanced before release). If it's inside firing range the enemy gets the modifier when in combat.

Shore bombardment works as before. RWG can't be used with naval invasions so in order to have both applied the RWG has to be in range
 
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Cap is 15% (unless it's gets rebalanced before release). If it's inside firing range the enemy gets the modifier when in combat.

Shore bombardment works as before. RWG can't be used with naval invasions so in order to have both applied the RWG has to be in range
Why can RWG not be used to assist a naval invasion combat in range?
 
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