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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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I can see the advantages of making railway guns, but what would be the disadvanteges of making them? Any downsides or is it just an all around good bonus to have in combat?

How does it affect supply? What about being transport across the ocean?
 
How hard-coded will be the movement on railways? Can we somehow mod units so they can move only on provinces attached to water? To create river monitors. How will sea transport work?
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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Looks good.
If you capitulate a country that has railway guns, how many do you capture? Is it the same percentage as convoys and equipment?
That is an interesting question since Germany used a lot of captured French railway guns, but the precedent for discrete items on the map like this (ships) is that they don't transfer at all.
 
This reminds me, it was mentioned previously that implementing divisions strat redeploying through railways would be attempted, does the fact that railguns are indeed restricted to it mean it was successful?
 
This reminds me, it was mentioned previously that implementing divisions strat redeploying through railways would be attempted, does the fact that railguns are indeed restricted to it mean it was successful?
Not related. That said, we do still intend to have strat redeploy at least favor railway.
 
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Not related. That said, we do still intend to have strat redeploy at least favor railway.
Please do let us know whenever you have a definite answer. :)

Strategic redeploy via railroads; fuel usage for supply trucks; and whether trade is affected by rail and port networks are probably the three biggest outstanding questions we have concerning logistics.
 
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The fact that this cannot be used independently of combat (like strategic bombing) is very disappointing. Like ballistic missiles, this should be useful for strategic bombing. In fact, it should be even more potent, being more accurate. It should have been implemented as some form of CAS or Tac/Strat bombers that have very short range and can't be shot down.
 
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They should passively damage enemy buildings in their radius. If you find a frontline becomes immovable due to fortifications and entrenchment you could bring railway guns up to weaken the line before an offensive. The other side would also then have to try to take out those guns before their defenses are weakened. That way the guns can be used as actual siege weapons.
 
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Nice.

  • Images are broken for me too. (now are working) If you can't see them, maybe read the diary on steam. They are working fine there (but the last link there is broken).
  • As many others, I'd also like to know how/if we can transport them oversea and if we can move them through allies/puppets.
  • Since they are basically land battleships, could we choose where to deploy them as we can for ships? Maybe any supply hub could be a viable deployment point.
  • It would be cool if we could make designs for them too, though I can see that more useful for modding.
 
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Since we can produce a specific number of Railway gun can we also set the factory to produce a specific amount of gun ,plane ,tank ? Like ship?
 
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Going to voice and unpopular opinion: Dissapointed they made them tactical fire support units, something they would be wholly ineffective on. Instead they should be used as a siege unit and fortress buster.

I.e Schwere Gustav would have been a poor unit to shell advancing tank formations (calling in arty is a long process, even during WW2. It is a reason why battleships wasn't used in this role, but destroyers, or why strategic bombers did not provide CAS) but it was used to weaken i.e Sevastopol.

I think HoI4 should include the possibility of pounding rear echelon units (something startegic bombers and battleships did) and saturate those areas.
 
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