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HOI4 Dev Diary - Supply and Mulberry Harbors

Greetings all, and welcome to today’s dev diary on the huge supply system update coming with the Barbarossa update. Before we begin, I’ll leave a heads up that this will be the last dev diary before we break for summer, so don’t expect anything new until some time in August at the earliest.

Since we last talked about supply, a few things have changed. We found that the way truck need could take off and spike was hard to deal with and that watching out so you didn't overload individual supply hubs was a bit too intensive. We also felt that the way the mapmode worked made it very difficult to project how well supply was flowing.

The iteration we have now aims at addressing these shortcomings. It's now possible for divisions to supply from multiple hubs. Trucks are now less of a strict necessity, rather something you can assign to hubs to make sure they can project supplies further away. Finally, the mapmode has changed to better show the spread of supply as well as current status for divisions.

Supply flow

From each hub connected back to the capital, potential supply is projected outwards - adding up when overlapping. This is represented by the brighter colors below. For each province in distance that supply needs to travel from a hub, there is a reduction in the amount as some is lost. The amount depends on various factors like terrain, crossing rivers etc. The dark purple areas below are reduced to local supply only, and the highlighted red-orange areas indicate locations where there are units suffering from significant supply issues.

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In the picture above, the Ukraine/Caucasus front is mainly struggling because it is overextending before the captured rails have been converted, so a lot of the rail network there is not operating. When a railway is taken over there is a longer cooldown when it gets converted for use by you (representing a combination of repaired damage, gauge-alteration, and general maintenance), and without connected hubs supply won’t flow.

How much you can output from each hub depends on the level of railways leading back to the supply capital, and the total max there depends on your industrial base (so Luxemburg can not feed as many as soviet union, for example).

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Here, the clock indicates rails that are not yet converted, and the hub icons with red crosses indicate that they do not connect back to your network.

Motorization

To increase the range of a hub (perhaps to help supply the front above better) you can choose to improve the motorization level. The horse icon on the right indicates no motorized supply from the node, but you can opt to toggle it to a higher state of motorization. Be careful, as this will cost you trucks which are taken from the stockpile.

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It is also possible to set the motorization level on an army, in which case it will automatically toggle on motorization for hubs that it uses without requiring further interaction from the player.

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There are also some other options on a hub. The star icon lets you move your supply capital to a new location, provided that you have sufficient surrender progress. This lets you get around issues where your capital ends up cut off or surrounded, but also comes with a period of bad supply as the new location is prepared.

The blue flag next to it lets you control allied access to the node. This can be a great way to flag to an AI that you do not want them on your front, or to stop them from joining a tight landing situation.

The rail icon lets you quickly switch to construction mode and extend rails from there while the green plus will automatically queue up construction for rails to combat any bottlenecks your node may suffer from back towards the capital. The chevron icon lets you prioritize train allocation if you are running low.


Floating Harbors

As part of No Step Back, we’re introducing a new dimension to naval invasions. Floating, or ‘Mulberry’ harbors can now be constructed once the appropriate research has been completed.

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These weighty and expensive pieces of infrastructure (don’t look too close at the numbers above hehe) aren’t intended for every-day landings, but are instead intended to represent the equipment used in large-scale operations such as the Battle of Normandy.

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Naval invasions utilizing a floating harbor will be represented by harbor apparatus placed parallel province targeted by the invasion, and will immediately create a stocked supply hub at their location:

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Used carefully, one or more mulberry harbors can keep a sizable invading force supplied without requiring the immediate capture of an important enemy harbor. Of course, harbors should remain amongst the first targets of any successful invasion, and the supply hubs created by a floating harbor will be temporary; lasting a matter of weeks or months, depending on the strength of enemy air superiority and other factors.

Of course, there is yet more to cover regarding supply, and we'll have another diary on this subject in the future, but I hope you like what you've seen so far and we’ll be seeing you again after summer!

Oh, and one last thing - one of the new loading screens for NSB is this awesome Polish cavalry, so we figured we should share it as a summer wallpaper for you (fear not, there will be a soviet one eventually!)
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The vision behind the painting was to present a more historically accurate depiction of the Charge at Krojanty. This was an engagement in the opening days of WW2, where the elite Polish cavalry surprised a German infantry unit at rest, charged before it could prepare for defense, and dispersed it. They later withdrew when faced with German armored cars.

This battle is famous because it started the, often officially repeated, ahistorical view of Polish cavalry charging German tanks and we wanted to try and make something more accurate (ignore the backdrop. we couldn't resist an epic sunrise on a field, but I hope the feel is there).

We have attached 3 different aspect ration wallpapers for you, and we can't let this opportunity go without a shoutout to @CreamGene our talented 2D artist responsible for this artwork.
 

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Perhaps lock scorched earth tactics behind the Mass Assault doctrine and the Desperate Defense branch of Mobile Warfare? I'm not sure how that would feel for players or how many historical instances of scorched earth tactics it would prevent.

At the very least, if scorched earth tactics are added to the game, I think adding increases to their destructiveness to Desperate Defense and Mass Assault makes sense
True, you need to research certain doctrines to allow this, especially in the early game it would be just crippling to the axis to a point of breaking the game
 
> Here, the clock indicates rails that are not yet converted

That's a clock for ants :p

Will trucks and horses suffer attrition? Will there be 'horsepower'?
That reminds me, horses aren't free either. Granted a "horsepower" resource is ridiculous, but the horse heavy german infantry divisions required a lot of extra feed. 10-15% of the divisional daily supply tonnage requirement went to feed horses alone.
So horse drawn logistic support, while not requiring fuel, should probably have a supply tax well in excess of the truck borne element.
 
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could the delay be split so that rails take damage on capture and the delay then checks for what gauge is used by the other country and applies a number betwen 0 and whatever so that civil wars because they are the same country thus using the same guage get no penalty except damage on capture while separate countries gets both penalties and with such a system you could have 2 peacetime countries that use the same guage with rail-lines bordering get trade bonuses
 
I feel like supply should flow from the state to the capital (without any losses between those transactions of course), as well as supply the units stationed there with the supplies the factories were producing.

i.e. The Tanks produced in Stalingrad which came fresh out of the factory rolled straight up to the front lines.

So what I'm saying is that the flow from the capital should be a lot stronger (cuz it contains the factories of the entire country) but if you have 5 factories in kiev that produce 3x infantry and 2x artillery those factories should then deliver their stuff to nearest unit that needs it like... i.e. some on the Romanian border

Now, this probably won't happen in a very long time, maybe not even with this DLC, but the next, but I feel like it's worth considering?
 
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Glad there's a way to ban allies from your supply node. However, it's still not a substitute for the complete lack of coordination tools between allies. I hope the blue flag allows you to ban specific allies from the supply node and not just everyone.

Not sure I understand how they changed the Supply Trucks since the first Dev Diary. I hope it's not dumbed down. The lack of sufficient numbers of Supply Trucks was a major problem for the Axis in the Soviet Union I think, because the Soviet infrastructure (especially roads) were so bad and the huge distances involved away from rail lines, they really needed trucks and never had enough.

Regarding the issue of Rail conversion. It's not as simple as it's being portrayed in the Dev Diary. Rail conversion was necessary for the Germans to do when they invaded the USSR because the Soviets used a different wider rail gauge (1520mm) than most of Europe (1435mm) did. Meaning the German trains couldn't operate on the Soviet rail lines until it was converted to the narrower standard European gauge.

Soviet stations on the rail lines were also too far apart for German trains because German trains carried less efficient fuel (coal). So the Germans had to build more stations. German trains were also heavier than Soviet trains which also required extensive modification of the Soviet rail lines when they invaded.

Not every country that invades another country should have to convert rail lines. This is important. In fact, most countries in Europe used the same standard European rail gauge (1435mm). I think Spain and Portugal used an even wider gauge than the Soviets (1676mm). Finland and Mongolia also used the wide Soviet gauge (1520mm) I think. The type of rail gauge that a nation uses should be a national modifier like a National Spirit. The Soviets had to convert the rail lines of the Baltic states (Estonia, Latvia and Lithuania - standard 1435mm) to wide gauge after they invaded. The Germans had to convert the rail lines of the Soviet Union to standard European gauge when they invaded.

Also, both the Soviets and Germans sabotaged their rail lines when they retreated. The Eastern Front was a total war in every sense of the term. If a rail line is sabotaged it should have to be rebuilt which should take significantly longer than merely converting it. Self sabotage of infrastructure needs to be in the game.

Also, in the Soviet Union all rail lines led to Moscow. It was the main terminus, the hub of the wheel. If the Germans had captured Moscow the ability of the Soviets to transport supplies from East to West would have been severely hampered. Cut off Moscow and the entire Soviet rail network would have been crippled.







Also, the Supply Trucks (Studebaker US6: The Lend-Lease ‘Deuce and a Half’) that the United States sent to the Soviet Union in Lend Lease was a huge game changer. It may have shortened the war on the Eastern Front by a year. It allowed the Soviet Army to be highly motorized and travel vast distances in single operations.

 
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To add to the choir here, there should be some way found for the supply trucks to use fuel too. I mean you could still have things like supply horses and trains that don´t use fuel, but if you want the fastest deliveries of supply to your divisions in the field trucks would be the way to go.
 
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This update just keeps getting better (especially being able to ban allies from fronts).
 
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Don't trample dreams of kids! Polish charging german tanks with cavalry or Japanese charging american tanks with swords... Informing people that such badass stories are not entirely true is like telling them that Santa is not real. It's cruel!
 
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Will we ever see the AI use these new floating harbors?
 
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What about:

Berlin–Baghdad railway


Standard gauge

In 1932, the Kingdom of Iraq became independent from the UK. In 1936, Iraq bought all railways in its territory from the UK

Decision for UK/Iraq = buying the railroads from Iraq yes/no in exchange for civil factory ......hmm

The Hejaz (or Hedjaz or Hijaz) railway (Turkish: Hicaz Demiryolu) was a narrow-gauge railway (1,050 mm)

Only german locomotives can used on this railway network or it has to be changed.


but it was (partly)closed in 1920 some tracks are in service till today, can nations in these region re-open this railway?
 
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Also in formerly east africa the Tanganyika Railway (German: Tanganjikabahn) has a 1000 mm gauge. In 2017 they constructed a standard gauge (1435 mm) line parallel to the meter-gauge


Iam not sure but it seems all former german colonies have 1000mm , and UK/French did never changed this. That would make the african continent a railway chaos

1024px-Railways_in_Tanzania.svg.png



In the former german south west africa germany used 1000mm gauges Swakopmund–Windhoek line,too
https://en.wikipedia.org/wiki/Swakopmund–Windhoek_line

Bahnstrecke Douala–Ngaoundéré Republic of Cameroon has 1000mm gauges https://fr.wikipedia.org/wiki/Transcamerounais

What does French/UK gauges were used in africa? Sometimes they used the CAP gauge ?

Does that mean for UK/French theyve to build other types of locomotives for their colonies?

Interesting isnt it?


 
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@podcat I know this suggestion is related to an earlier DD but I was hoping to catch more people's attention so they could weigh in on it. I was wondering, as you are going to limit the pop-ups for war declarations, how about also doing the same for situations where a lot of NAP offers appear and/or access requests, if they're coming from individual members of an alliance. It happens a lot when I'm either my own faction [not one of the big three] or not in a faction, and my enemy{s} decalre war on other nations/factions, I get deluged with such offers. It would be nice to just agree/disagree to the faction leader's request/offer, and the others are either included [access] or they get asked by their faction leader if they are able to honor the offered NAP. It would just save the player a lot of time, especially when the AI goes down a decolonization path.

Nicer still would be the option to agree to limited access - where you tell the ones asking that they may only send (x) amount, and maybe even limit where thye go, so they don't muck up your logistics.
 
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I am very concerned about naval invasions in the upcoming update. Naval invasions in the game are already too large imo. The biggest naval invasion in history was D-Day which had about 8 Divisions landing on the beaches at once. Plus there 2 or 3 Airborne Divisions landing behind the beaches.

However, in the game you can do much larger invasions than that. And Mulberry Harbors will make it even easier I think. I hope naval invasions are rebalanced to be more realistic in size when the DLC releases.

P.S. Also, there really should be a specific Naval Mission for defenders to sortie their Task Forces/Fleets and try to stop a landing that is going on. The Germans would have done this on D-Day if they had any warships left and the capability. They tried with with a few ships and Eboats if I recall but were unsuccessful. However, with a big enough Fleet it should be possible. Or if you want to throw your small Fleet against the naval landing in a suicide mission it should be possible.




 
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They tried with with a few ships and Eboats if I recall but were unsuccessful.

They had a handful of torpedo boats as well, and had a crack at sending U-boats into the channel. They had some luck, but by this stage the Allies' strength on the sea and in the air meant they had a pretty hard time of it. Germany also used aerial mining, which took a toll, as well as some more exotic weapons like explosive motorboats and human torpeodes.

More broadly, your concerns about the size of naval invasions are sound, but it's important if invasions are reduced to more historical sizes that it's possible to limit the build-up of the defender with airpower (for example, the bombing campaign prior to D-day that shut-down most of NE Europe's rail network, making it very hard to send reinforcements to the beachhead), and also to be able to keep sending new troops in over those beaches (it was only eight divisions on day one, but the amount of personnel and material they landed over the beachhead was phenomenal - I can dig out the stats if it'd help).

At the moment I kind of think of large invasions as not just the first wave, but also some of the following waves as well, and that makes the numbers more sensible.
 
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I wouldn't be surprised if someone already addressed it, but how are the rail networks generated?

Are they purely historical (meaning every mod has to set them up ahead of time), automatically generated based on infrastructure and terrain (personally I think this is the optimal, albeit code heavy option), or can you build them yourself the way you build bunkers (the micro heavy option)?
 
I wouldn't be surprised if someone already addressed it, but how are the rail networks generated?

Are they purely historical (meaning every mod has to set them up ahead of time), automatically generated based on infrastructure and terrain (personally I think this is the optimal, albeit code heavy option), or can you build them yourself the way you build bunkers (the micro heavy option)?

They have tried to replicate the networks of the time (or at least people have been sharing maps of the rail networks of the time). Mods will have to do similar.

You can then build extra if you want but they intended it to be expensive so it's not like civ1 (or vic2) where every possible tile has the max railroad it can.