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HOI4 Dev Diary - Mines and Minesweeping

Welcome to another glorious Wednesday! Today we are going to be talking about mines and mine sweeping. Historically hundreds of thousands of mines were laid during WW2 and with Man the Guns you too will be able to do so in Hearts of Iron.

From a gameplay perspective mines do a lot of interesting things. They add more interaction with the naval layer of the game, create a weapon both for smaller naval nations to fight bigger ones, and for big ones to try and limit where the enemy can get to them.

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As you may remember from my presentation at PDXCON, I talked about adding a ship designer to Man the Guns. It is not quite ready to show off, but it’s important to know that sweeping and laying mines are something you will be upgrading or redesigning your ships to be doing. Minelayers and Minesweepers are not actually new ship classes. In my screenies I have destroyers that can both lay and sweep mines for simplicity, but as @Archangel85 pointed out earlier “I am probably going to have a ton of different destroyer designs”... anyways, details on the designer is for a future diary when it is done, but hopefully it helps explain some stuff in the proper context.

Mines are unlocked from techs and require ship designs fitted to deploy them. Destroyers and light cruisers can do this, as well as submarines with the correct tech (excellent if you as Germany want to make things even more dangerous for the British at a lower risk to yourself). Mines can also be dropped from the air with later game techs. Both of these unlock new missions for navies and airwings.
mine_techs.jpg


Mines can be made better and better through research. You start off with Contact Mines to unlock them. Then their destructive power is improved with Magnetic and Acoustic mine techs and finally with Pressure mines. At the bottom (heh) you also see two techs for submarine mine laying. The first is just the basic ability, while the second improves efficiency a lot by allowing mines to be deployed through torpedo tubes, thus no longer requiring you to design specialized minelaying submarines.

To get rid of mines you need minesweeper capable ships. This unlocks the naval mission to sweep mines and will slowly work at clearing areas. Minesweepers are also nice to include in your fleets as they will then be assumed to travel ahead of the fleet and reduce the impact of mines on them. I suspect a good design combo will be anti-air and sweeper on screen ships to be your passive defense when in enemy waters.
mine_report_map.jpg


There is also a passive “degaussing” technology that can be researched after Magnetic Mines. This was employed during WW2 to reduce the magnetic signature of ships and thus make them less likely to set off mines.

It is also possible to sweep mines from the air, but this is a late game, expensive technology and unlocks a new air mission for bombers. This was something that was done sparingly and in shallow waters, but for example was successfully done to evacuate the Dutch royal family to Britain.

What do mines exactly do then? Well they blow stuff up! Their explosive results are shown on map as accident reports, and there is a new tab too under the Naval Losses statistics interface if you want to dig into details. As ships operate or move through a zone they will risk running into mines. This can lead both to minor damage as well as outright sinkings. The best ways to avoid this is to make sure the area is swept free of mines, but as mentioned above, having your ships travel with sweeping capable ships makes it safer for all.

mines report.jpg

This is not all through, mines have several passive effects.

Naval superiority - Having mines in an area helps amplify the effects of your navy (after all they can concentrate more effectively knowing where the mine fields are). This can be seen in our new naval area screen, which is the naval equivalent of the state view:
travel.jpg


Other than that and blowing ships up mines will slow down enemy ships (since they need to be more careful) and increases the invasion penalty to coastal area. So mines are both good offensively and defensively.

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Mines can only be laid while at war and will start to disappear over time once a nation is completely at peace. You always know how much mines there are in an area, so you know how to deal with them and take them into account. That means that with the new naval access controls you can tell your ships and convoys to avoid heavily mined areas, but of course this may make it a lot more predictable for your enemies where to hunt. Having an advantage in the encryption-decryption war will also add a certain amount of passive defense against mine effects as you may have some information about their positioning.

See you all next week for more Man the Guns info!

Rejected Titles (for extra good reason this time...):
- This War of Mine
- Vengeance is Mine sayeth the Lord Admiral
- Do you mine’d
- This feature was made in cooperation with the seagulls from Finding Nemo
- Mine = blown
- The Ship Designer isn’t unfinished, it’s just a bit shy
- Minesweeper 2000 Online HD Edition
- Mine over Matter
- Mine the guns
 
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@Axe99
How do I feel about this?
Will this be as unimportant for the navy as "acclimatization" is for the army? Since acclimatization was released there has been one thread made about it and one post on that thread. Since no one ever posts about acclimatization, mentions it etc. which tells me I was right the day that it was introduced that it would be a non-starter and would amount to nada. Which it has. Why do I now have the same feeling that "mines" are going to give me just as much of a rush as acclimatization did, a nada. At this moment I'm not feeling mines whatsoever.

Will the AI use it? More important question; will the AI know how to use it properly?
 
Hi Podcat, will the naval commander trait get revised as well?
I think it's been confirmed somewhere that naval traits will be expanded and given a proper interface, like land traits did in WtT.
 
@Axe99
How do I feel about this?
Will this be as unimportant for the navy as "acclimatization" is for the army? Since acclimatization was released there has been one thread made about it and one post on that thread. Since no one ever posts about acclimatization, mentions it etc. which tells me I was right the day that it was introduced that it would be a non-starter and would amount to nada. Which it has. Why do I now have the same feeling that "mines" are going to give me just as much of a rush as acclimatization did, a nada. At this moment I'm not feeling mines whatsoever.

Will the AI use it? More important question; will the AI know how to use it properly?

Haha, you should never leave your feelings at the mercy of anyone else but yourself :). More seriously (as I don't think that's what you were actually doing :)), I think mine warfare has a lot of potential, and everything we've seen so far sounds good, but it's impossible to say anything with confidence until we can play the final implementation ourselves. By the look of it, the feature looks like it would enable things like:
  • Defensive mining of coasts to make it more difficult for invading forces, opening them up to damage and slowing them down, making them more vulnerable to aircraft or interception by opposing fleets.
  • Attritive offensive mining, causing damage to warships and damaging trade.
Both cases could have a significant impact on the naval war, and I am cautiously very excited :).
 
Any luck improving the big issues that cripple this game in single player?

I have avoided the game for about six months, but I decided to do a play through with France yesterday. 1) Germany and Italy never used their airforces in the West. They never once sent their plans to France or Belgium. 2) The 1 casualty to 20 or more bug is still in full effect. AI Italy would launch single division attacks against mountain forts. By late 1940 Germany and Italy had 4.5 million casualties, France had 110k. 3) UK AI lost 750k men but never participated in a battle. They only had 30 division in late 1940. I'm assuming the all drowned in the med, as Italy was responsible for most of the casualties.

Are other people still having these issues, i.e., do I have a corrupted game file? This game has been out for years and the other games in this series were in much better shape at this point. I see Paradox keeps adding bells and whistles but where is the discussion on the main game?
 
Good example of seamine warfare might be Soviet evacuation of Tallinn and Jumida minefield.

Also after Continuation war Finland was decreed to clear minefieds from Gulf of Finland, example of clearing up process after peace (took years tho), but information about fields were probably one item about peace deal agenda.
 
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@Axe99
How do I feel about this?
Will this be as unimportant for the navy as "acclimatization" is for the army? Since acclimatization was released there has been one thread made about it and one post on that thread. Since no one ever posts about acclimatization, mentions it etc. which tells me I was right the day that it was introduced that it would be a non-starter and would amount to nada. Which it has. Why do I now have the same feeling that "mines" are going to give me just as much of a rush as acclimatization did, a nada. At this moment I'm not feeling mines whatsoever.

Will the AI use it? More important question; will the AI know how to use it properly?
The biggest difference between acclimatization and mines seems to be that acclimatization only gets almost unnoticed bonuses in a terrain, where mines will actively damage and destroy ships. So, unless it takes mines forever to dmg/sink I imagine you will feel them a lot more than acclimatization.
 
Any luck improving the big issues that cripple this game in single player?

I have avoided the game for about six months, but I decided to do a play through with France yesterday. 1) Germany and Italy never used their airforces in the West. They never once sent their plans to France or Belgium. 2) The 1 casualty to 20 or more bug is still in full effect. AI Italy would launch single division attacks against mountain forts. By late 1940 Germany and Italy had 4.5 million casualties, France had 110k. 3) UK AI lost 750k men but never participated in a battle. They only had 30 division in late 1940. I'm assuming the all drowned in the med, as Italy was responsible for most of the casualties.

Are other people still having these issues, i.e., do I have a corrupted game file? This game has been out for years and the other games in this series were in much better shape at this point. I see Paradox keeps adding bells and whistles but where is the discussion on the main game?
Play some mp, its pretty great and a lot of the issues in sp are void in mp due to people and rule sets. Though, I can understand the frustration of the blatant AI issues.
 
Some of the RN's minelayers were very fast ships - the Abdiel class minelayers could get to nearly 40 knots.

I like how the British disguised them to look like the Vichy destroyers/light cruisers.

Interesting read, thanks. (The wiki on the Abdiel class that is.)
 
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Here's hoping that we get some resource rebalancing on the Map as it is most naval powers have basically no reason to defend their assets overseas, the fact is it's a pain to fight in Africa and there are just pathetic rewards available for having done so. I'd also love to see commando units play more of a role since they are in such limited supply now some Decima MAS frogmen limpet mining aircraft carriers would go a long way to enhancing the Mediterranean experience especially.
 
This opens up a lot of sneaky stuff. The UK mining the heck out of the south China and North China Coasts before Japan declares war. Gulf of Thailand? Yep, mined to the point Siam has no international trade. The US can use the Phillipines to mine everything to death. North Africa? Forget about ever seeing an Italian supply ship make it there.

Heck, Axis can mine Atlantic wedt of Gibraltor and get modt of UK shipping.
 
Exploit incoming!
Italy never finishes the war in Ethiopia (or for NF sake dow another minor) and uses her fleet to mine the entire globe.
Since there's no mine decay in war time, when Italy joins WW2 in 1940, 4 years of mining the globe could send the entire Allied fleet to the bottom of the oceans.
Concentrated production of mine layers from 1936 and tech rush included.

That'll be the first thing I'll do in MtG!!
Don't you need to defeat Ethiopia to unlock the bulk of the focus tree?
Also, Podcat mentionned mining at some places could give a war goal against the person who lays them.
 
Don't you need to defeat Ethiopia to unlock the bulk of the focus tree?
Also, Podcat mentionned mining at some places could give a war goal against the person who lays them.

Like I said, for NF's sake you could simply dow some generic minor after Ethiopa.
 
With the probable use of minelaying exploits to gain an advantage as previously discussed, the simple way around it is to allow minesweepers to work without a active war, earning exp points and allowing even better minesweepers et al.

I am pretty sure that the Swedes had minesweepers active in the Baltic throughout the whole of WW2