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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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  • 191Like
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¿Supongo que la resistencia tendrá más operaciones de sabotaje o no habrá cambios allí?
No dijeron nada, salvo la toma de Varsovia, la verdad no creo, están hasta las manos con otras cosas
 
'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.'

96083537_2558438991046017_4764798308289871872_n.jpg

After all those years... Is this real?
 
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What about pipelines? Are these also abstracted into "rail" connections?
I'd rather not have railways where there were only pipelines. I don't really see the point in pipelines tbh. Those that come to my mind are situated in a way that makes them not really targets at least in the Middle East. Any invader making it as as far as Haifa will most likely also make it to Kirkurk to take the oilfields. If not oil would be shipped down the rivers, so they are a bit pointless.
 
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Will equipment replacement be geographically relational? That is, will military factories be considered a source of replacement equipment, or will all military factories continue to go into a general pool to be reinforced from a capital, victory point location or industrial hub?
 
With the button that prevents Allied units from using the front-line would that also affect Allied air-craft from hogging air-bases? Every time I play the US and invade France the UK just floods the air-fields in France preventing me from using my own air support.
 
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To echo at least half a dozen other people, it's worth the complexity. Please reconsider if it's at all feasible to implement fuel consumption by supply trucks.


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.


I think the ideal solution would be to catalog the various rail gauges worldwide, assign a unique value to each, and calculate a binary cost for converting railroads based on whether a local gauge is different from your national gauge.

If you're fighting a civil war, presumably the railroads you're fighting over are all the same gauge and can be quickly integrated into your network; if you're invading the Soviet Union, integrating the conquered railroads will take longer.

Scorched earth was almost universal to some extent. For instance the British when in retreat in north africa dumped thousands upon thousands of gallons of fuel into the sand rather than allow Axis forces to capture fuel. It wasn't a doctrine choice as much as not giving equipment or fuel to the enemy.

That was a theatre where everyone was in short supply.

Once again fuel is half of supply.

The other half I guess were trucks and ammo carriers. Which were basically tank chassis without a gun. And in some cases when they had attrition, they would turn the ammo carriers into functional SPGs.
 
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"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."

All hail The Blue Flag!

Just last night I had a vanilla ironman playing as Egypt ruined by my allies sucking up the supplies. It got to the point that I could not get in on any front as the allies were using up twice to almost four times as much supply as could be provided. It was a shame, too. Such a good game until then.
 
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Why don't you just make supplies produced by a certain number of civ factories instead of getting them from nowhere
They could use an indirect approach using the cap from mils, the ic drift to supply is not the key point, it's the max value the important thing to prevent crazy things like Japan rajh
 
That sounds like it would quickly become a mess of special modifiers and complexity. Better to just have a general penalty for non core rail.

It wouldn't.

Rail gauge in different countries was generally standardized by the end of the 19th century. Even now, there are only 13 different standard gauges across the world.

So most of Europe was one rail gauge with a switch as you moved to the Soviet Union, but the base rail gauge for a given network of supply points should just be set at the start of the game with the owner of said supply points being given the option to change it for a cost of some industry and a supply penalty for when supplies switched.

Rail_gauge_world.svg
 
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Why don't you just make supplies produced by a certain number of civ factories instead of getting them from nowhere

This was how it was done in every HOI until 4.