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HoI4 Dev Diary - Subs and Convoy Raiding

Greetings, I am a game designer new to the HoI4 team. This is my first dev diary, so be gentle ;). Also, sorry for the late post today. I am an American and when it comes to WW2, we show up late.

Today’s diary entry covers our improvements to submarine convoy raiding. In past versions of HoI4, submarines have not really pulled their weight. We have sought to change that and make them worthwhile to build. I recently put these changes to the test by playing a Germany campaign.

My naval plan as Germany was to exploit the central Atlantic and Cap Verde Plain with a submarine wall. This would hopefully prevent England from getting necessary resources from the USA and the colonies. The biggest effect of this resource shortage would be the UK running out of fuel, crippling both their navy and air force. This would hopefully open the UK to sea lioning before the USA joins the war or at the very least, make winning the air war very easy and cause permanent damage to the UK’s fleet.

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We have previously mentioned the spotting system, and how naval task forces are revealed over time. This functions a little bit differently for subs. Spotting an enemy sub outside of combat is based upon chance. The chance for this to happen is based on how quickly the spotter will spot their target. However, it is possible for a submarine to have a large enough advantage in spotting that the submarine task force will not be able to be spotted. However, convoy escorts will still be able to fight against submarines once combat is initiated, even if subs are not normally detectable by enemy taskforces on the map.

This system creates a tech race between sub stealth and sub spotting, with subs having a better chance of getting an advantage in the early game. Previously, submarines would eventually be detected and killed no matter how good at hiding they were. This is no longer an inevitability.

Before beginning the war, I made sure to complete the German naval focus line down to “U-boat Effort.” Along with getting a research speed boost and some dockyards, the focus gives Germany access to a “Cruiser Submarine.” This sub is a sort of tech 2.5 Sub with extended range, some unique module options, including catapult planes, and the ability to be upgraded with a snorkel.

uboateffort.png


Part of my plan for giving England a hard time included mining up the English Channel. I executed this plan with a cruiser sub equipped with naval mines and plane catapults. These plane catapults boost the sub’s surface detection, giving them an advantage in being detected and helping them remain invisible, at least for the first couple years of the war.

Sub Minelayer.png


I made a tech 3 sub-variant for minelaying the Eastern North Sea and a tech 3 raider-sub for Cap Verde Plain. When I demanded Danzig from Poland in August of ‘39 I had 79 Subs of various roles ready and much of the Trade Interdiction doctrine complete. This focus on raiding will give my subs a further detection advantage over other countries that have yet to complete their convoy escort doctrines.

Speaking of the naval doctrines, we have made some changes all around to account for the new combat system and apply a bit of balance. In particular, we have given some buffs to the Trade Interdiction doctrine to make it more attractive than it was previously. We have added additional survivability for submarines and more of an edge in surface detection values. Capital ships have received some defensive increases as well.

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Torpedo reveal chance is a new thing for subs. When subs are in combat, attacking no longer guarantees that a sub will reveal itself. Baseline, subs have a 50% chance to reveal themselves when launching a torpedo volley. This can further be improved through doctrines and admiral traits. This makes ambushing protected convoys safer and retreating when too many destroyers show up easier.

In my campaign, I capitulated France in early December of ‘39. To help with the Axis’s naval situation I formed Vichy France. Before France fell they had been contesting my raiding of Cap Verde Plain to the best of their ability, but I was still seeing some success. Forming Vichy France put more ships in the hands of the Axis and would further help to stretch the limits of what England could endure at sea.

With Vichy France on my side, early 1940 saw a massive spike in convoys raided as Cap Verde Plain and the Mid-Atlantic were now completely covered. By this point, I had ~20 dockyards producing subs for minelaying and raiding. All of my newest tech 3 Raiders were seeing great success in under the guidance of Karl Dönitz. Even when contested by British convoy escorts, they were able to get a respectable amount of kills and retreat. Naval bombers were also ramping up operations in the English channel.

casualties.png


We have added a new effect to convoy raiding, war support reduction due to raiding. By mid-1940, Canada had been raided to 0 convoys and had their war support reduced to a point where they were no longer able to support War Economy. This helps to promote raiding and discourages blunt forcing convoys through an area where you are being raided.

Canada War Support.png


By early ‘41 the UK had been choked out of convoys and fuel and was unable to keep their navy running and were about open to a naval invasion. By mid ‘41 I had naval invaded the UK and was Setup for an attack on The USSR.

See you all next week!

Rejected Titles:
-Raiding and Reaving, 1940 edition
-Subs, they're not complete trash now!
-Under the sea, Darling its better
 
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With Vichy France on my side, early 1940 saw a massive spike in convoys raided as Cap Verde Plain and the Mid-Atlantic were now completely covered. By this point, I had ~20 dockyards producing subs for minelaying and raiding. All of my newest tech 3 Raiders were seeing great success in under the guidance of Karl Dönitz. Even when contested by British convoy escorts, they were able to get a respectable amount of kills and retreat. Naval bombers were also ramping up operations in the English channel.

View attachment 428584

We have added a new effect to convoy raiding, war support reduction due to raiding. By mid-1940, Canada had been raided to 0 convoys and had their war support reduced to a point where they were no longer able to support War Economy. This helps to promote raiding and discourages blunt forcing convoys through an area where you are being raided.

View attachment 428586

By early ‘41 the UK had been choked out of convoys and fuel and was unable to keep their navy running and were about open to a naval invasion. By mid ‘41 I had naval invaded the UK and was Setup for an attack on The USSR.

If the AI is this helpless in the naval game this far into the development of the expansion, then that is very worrisome news to all the people that want to play singleplayer.
 
@podcat "My naval plan as Germany was to exploit the central Atlantic and Cap Verde Plain with a submarine wall. This would hopefully prevent England from getting necessary resources from the USA and the colonies. The biggest effect of this resource shortage would be the UK running out of fuel, crippling both their navy and air force. This would hopefully open the UK to sea lioning before the USA joins the war or at the very least, make winning the air war very easy and cause permanent damage to the UK’s fleet."

This means we will have decentralize fueling system in which we spread accross our fuel? might be an interesting feature hopefully not to late to be implemented in the DLC, or maybe is surprise with the DLC and i managed to spoiled it.

Best Wishes!
 
Will be able to manual set up trade routes? and maybe get large convois instead of many small ones? then the player have the ability to guard the atlantic,get 50 oil instead of the 20 needed and has still 30 in reserve instead of risking his convois every month. the same can be done with lend lease as well (small number per month or 1 big shipment with many convois)

also to drew manual traiding routes prevent the soviet union sending convois into the baltic sea when at war with germany, because the ai does that as long as germany dont kill denmark. so your concois go and die there like lemmings
 
Very hands-on approach for a DD I like it, not every time but from time to time this works very well.
Two questions, will we get a DD next week? and will we get to see the 3D and 2D art soonish? As in December or January?
 
Looks very promising. I'm looking forward to getting my grubby grabbers on this...
 
Cheers for the DD YaBoy_Bobby, and great first-up DD :D. It's wonderful to see commerce warfare and subs getting more attention - of the approximately 33 million tons of merchant shipping lost in the second world war (on both sides), more than 23 million were sunk by submarine. While there's no question that the biggest issue was screens being unduly powerful against submarines, has the situation where one submarine could take out 20 convoys been resolved as well? Either way, things are looking heaps better - looking forward to a much more engaging battle of the Atlantic once MtG launches :). Also, and importantly, do you have a favourite WW2 submarine?

For a pic for this DD, here's an 'on-expansion-topic' submarine - the Dutch KXVIII - turns out (as I recently discovered) as well as being quite successful against the Japanese navy, the Dutch also operated submarines in the North Sea (although not this one) in 1940. Note the cool external swivel-able amidships TTs :cool: (the French built some subs with this kind of arrangement as well).

KXVIII small.jpg


All of those points sound more like "The German surface raiders made a good fleet in being that required the British care about them" than "The German surface raiders were a wise investment for raiding convoys to defeat a superior naval power in a struggle on the ocean."

I bring it up, because I am always reminded of the Royal Navy's assessment of the merits of the Anglo-Germany Naval Treaty. The admiralty preferred a balanced German fleet (which is what the AGNA stipulated), because it could be beaten easier than a submarine fleet.

I've always contemplated how many u-boats Germany could have built and maintained for the cost of Bismark and Tirpitz. And how much further u-boat research could have gone before the war if research efforts had focused on u-boats instead of bigger battleships. I know Germany building up a large u-boat force would have provoked a harsher reaction from Britain (since they and France are the only real targets of such a navy), but I'm not sure the German surface fleet ended up justifying its cost during the war.

In isolation, had Germany just wanted to fight a war solo vs Britain, I don't think there's any question that subs are the way to go. However, in a situation where the UK has to divide its forces between Germany and Italy, and then between Germany and Italy and Japan, a Germany that basically 'gives up' contesting the surface of the Atlantic frees powerful surface forces that are likely to make life much harder for Japan and Italy. If Britain, for example, could deploy much of their fleet, including their carriers, to Singapore in December 1941 (and the US doesn't have to send as much of its fleet to the North Atlantic as well), Japan is in a much more precarious position.

That said, even in a 'just Germany vs Britain' war, the 175,000+ tons of battleships (KGVs) and 88,000+ tons of aircraft carriers the Brits built between 1937 and 1942 (or so) is a lot of resources that could be redirected to escort vessels. While I still think Germany would have been better off in a 1 v 1 situation going with subs, it's important (and I'm not for a second suggesting you were doing this yourself, am just mentioning this as I know others have) not to assume '300 German subs vs the Royal Navy as it was at the start of WW2', as historically nations tended to build their fleet based on the challenges they expected to face, and while it's all counterfactuals and unproveable, I'd wager a Germany building subs like the clappers would lead to faster and stronger British rearmament, which isn't necessarily in Germany's best interests (in a historical playthrough kind of way).
 
My naval plan as Germany was to exploit the central Atlantic and Cap Verde Plain with a submarine wall. This would hopefully prevent England from getting necessary resources from the USA and the colonies. The biggest effect of this resource shortage would be the UK running out of fuel, crippling both their navy and air force. This would hopefully open the UK to sea lioning before the USA joins the war or at the very least, make winning the air war very easy and cause permanent damage to the UK’s fleet.

It's all I really ever wanted. Great stuff.
 
Greetings, I am a game designer new to the HoI4 team. This is my first dev diary, so be gentle ;).

A newbie, eh? Don't worry, after the ritual hazing you will no doubt be accepted as part of the tribe. The hazing isn't even that bad; it involves shaving cream, tin foil, and a rather odd bit pubic topiary. After a while you will get used to the hair cut. :D
 
Is this a bug ? I played as morocco with golden century patch, but the sudanese expedition doesn't fire off. I have both the provinces bordering TUAT. And the year is already 1566. I couldn't find the forum for bugs. That's why i post it here
First step is to go to the eu4 part of the forum not a totally different game.

Then you need to link you steam account to the forum, there will be a guide some where at the top of the thread list telling you how.
 
German cruiser submarines are all well and good, but will the French be able to build submarine cruisers?
 
They already stated that they will not. There would be no point in this at all other than as a gag ship for silly playthroughs by youtubers like ISP.

They said that subs with guns are stupid and will not be in the game. Not that the French cruiser subs will not be represented.

Stuff like the Surcouf get special variants. some from start some from focuses
 
This is the first Dev Diary for this expansion that has me worried. The changes are all welcome, but the published result screen makes me think that the AI is just not up to the task and the game will be an even easier cake walk for the single player.:(
 
Well as long as submarines don't try to go head on against enemy destroyers as their first target and get utterly destroyed in the process. They should be sneaking around to try and "backstab" battleships and aircraft carriers, otherwise they'll remain useless in fleet vs fleet battles

That depends. Historically a tactic sometimes attempted by submarines when attacking a convoy was to try and ambush the escort destroyer first, before the DDE were actively hunting for them ( because once they were aware of a uboat threat they were almost impossible to hit due to speed and maneuvering ). This was not as easy as hitting a freighter but could still pay off because it made future attacks much easier.

If I remember correctly the German submarines sank about 40 or so allied destroyers during WW2, so it would be a shame if it wasn't possible to sink DDs with submarines at all. A stray torpedo intended for another target had enough explosive force to often split a destroyer in half.


Ofcourse I agree that the current situation where submarines only fire on destroyers if they are present due to them rushing forward first is very silly, but it seems like this has been fixed if you read last weeks DD about naval combat.