SUPPLY INTERDICTION NOT RIGHT

[Phoenix100]

So this happens with monotonous regularity now. Interdiction - 100% - of supply columns in the circs below. I have a clear line of supply. The only enemy that could possibly 'shoot' the trucks up is across the other side of the bleedin Waal!!!! It's not right. How can the trucks get shot to pieces when the flot troops are doing ok?

[rfrizz]

I have mentioned this before. I think some work was to be done to make supply runs "smarter" but I don't know if it was implemented. It seemed to me that the supply runs were taking the same approach and getting hammered each time.

An example is in the St Vith demo. If you play as USA, and hold Sankt Vith along with Breitfeld XRoads, the Germans love to hide a unit in the forest just east of the road from Breitfeld to Vith. When the virtual supply trucks go by,that unit hammers them. There are other places to hide supply-line killers.

My objection was the apparent use of the same route repeatedly. After two convoys hve been hammered in the same place 2-3 times in a row, wouldn't the route be changed?

Something that just occurred to me for the "wish list" would be a report from the convoys indicating the general area that the interdiction came from. That would be intel that you'd think would be available to an operation commander.

[dazkaz15]

I have been playing the same scenario as Phoenix over the last few days, and although at first I was sceptical as the reason seemed to me to be the bridge, I can now categorically confirm, that there is a problem with the inept, supply column drivers.

I first noticed the problem not at the Arnhem end but in the Nijmegen end of the battle with the American airborne depots.
Within a very short time, I was completely out of vehicles to transport supplies in all of my Regimental bases.

This left the entire 82nd Airborne completely useless, in very short order.

I even sent a Bn back to the base to see if they would hand me some if I got close enough, but they refused to give me even a bean.
There shortly followed an almighty bombardment on that stubborn quartermaster, where I decided to give what 75mm rounds I had left back to that useless well stocked depot.

If we have to have an abstracted supply, then we are going to need to recruit some better drivers, that have the sense to not drive past the 30 other burning supply jeeps on the road, but look for an alternative route instead, or park up somewhere safe, and manhandle the supplies the remaining few hundred meters.
It would even be acceptable for him to report that he couldn't get though, and that I would need to better secure my supply lines, than to drive blindly on into a storm of enemy gunfire, and destroy such a valuable, and vital piece of equipment.

This is the other bug that I was referring to on the support forum, that I need more time to write up properly.
I have a save of this happening, well actually I could have hundreds, because it was happening every few minutes at the start of the scenario, until I ran out of Jeeps, but the one I have shows quite clearly that there is no sensible reason for this to happen as regularly as it is.

[Phoenix100]

That's one part of the issue, I think, Daz. You can get round it by designating the airborne SEPs as ground SEPs, then they have an unlimited supply of jeeps (though that's unrealistic and silly, of course). But that doesn't avoid the issue of where all this interdiction is coming from. As I've said before, it's all coming from beyond the flot, and that really doesn't seem right to me - not when 100% interdiction happens with monotonous regularity (by day, at least). And not when the front line troops are stubbornly in there and the enemy can't oust them and they should be able to provide plenty of suppressive cover for a few jeeps to get through. Try to imagine the situation in the picture above - a company surrounded by 4 other companies (8 if you include those slightly east of the position), dug in and shooting across the river at the enemy troops over the other side with sufficient weight of fire to prevent those troops getting across the bridge. Their jeeps arrive no more than 100 metres further back, in a built up urban area and again and again are totally destroyed by fire form the opposite bank?? It surely wouldn't work like that. The supply - or some of it - must get through.

[Arjuna]

Send me a save and I'll take a look at it a bit later. Right now I am in the middle of the swamp battling several crocodiles.

[Phoenix100]

Don't worry about it, Dave. Let us know when you're out of the swamp. Meanwhile I'll work up a smaller scenario to test these supply issues, I think.

[dazkaz15]

ORIGINAL: Arjuna

Send me a save and I'll take a look at it a bit later. Right now I am in the middle of the swamp battling several crocodiles.

Wow nice one Dave!

Keep them hands inside the boat mate, there too valuable to us for you to lose

[Phoenix100]

Will you send a save, Daz? I'll work up something tiny to test these theories outside that scenario.

[Phoenix100]

So. I set up Joe's Bridge to experiment with this and here's the first result. There are NO Allied forces nth of the canal and no bridge to get over save the one the subject of the bridgehead here - Joe's Bridge. The Axis force here is beefed up, using the stats, but the Allied force coming at them is about 20 points more powerful (roughly 50 points axis, 70 points Allies), plus the Axis has only 20 Panther Gs and the Allies have a more numerous tank presence. So it's roughly like what happens in the Arnhem scenario, only this time the Axis have the bridgehead. The result? Within 6 hours I'm getting streams of supply interdicted 100% messages and a handful of red no supply route boxes (followed by surrender, usually, after a couple of hours without supply). So what is happening is that the Allies are interdicting supply just by engaging with the enemy, and/or targeting that vital vulnerable route across the bridge with arty or direct fire and interdicting like that. For what it's worth I didn't see any arty flashes landing on the supply route itself (as opposed to on units), so I would think that the engagement conditions alone interdict the supply where there is sufficient counterweight of firepower. But the bridge clearly makes this easier somehow, because see the next post and next photo, where I take the bridge out of the picture.

[Phoenix100]

Now we move the action over the canal. The result, it takes about 6 hours longer for the 100% interdiction messages to start, but after that it's the same picture. And, on surrender, there are no Allied forces infiltrating, so the interdiction is all happening from over the flot. Why 6 hours longer? I'm not sure - either the bridge choke point made supply more vulnerable in the previous run through, or it took the Allies a bit longer to get sufficient weight of firepower over the narrow bridge and into range.

[Phoenix100]

Now I've evened out the forces - both sides have roughly 60 points, though the Allies have more armour in the mix. Note what happens below - the interdiction happens at the point of contact - where there is the greatest weight of firepower applied by the allies (at the point of the bridgehead). Which suggests to me that it is the engagement conditions alone which mean that supply is interdicted. Not (at least not significantly) sniping at the supply route way behind the flot, though clearly that does happen as well, but not if you haven't got a general weight of firepower sufficient to produce that effect. In this run-through only those units facing a heavy specific attack had their supply interdicted. In previous run-throughs, when the allies had a greater overall weight of firepower, then interdiction happened away from the front line engagements too (as if, literally, someone was shooting anything going across the bridge).

[Phoenix100]

Conclusions? I don't think much is broke. The only thing I think is broke, in fact, is that you can't switch off attempts to supply troops where interdiction is going to happen or has already happened (not even ticking the min supply boxes works). Which means you eventually have no trucks to supply the troops with IF - and only if - your SEPs are air drop or airlanding SEPs. A quick fix for this issue, one which will 'simulate' better drivers, in effect, is - for the airborne scenarios - to go into scenmaker and convert the SEPs to ground SEPs (as I understand it these have an unlimited supply of trucks). Then - for the purposes of worrying about how many trucks you have left - just ignore those messages telling you supply was 100% interdicted. Pretend that what happened was that your drivers saw the interdiction and turned back, with no loss of trucks.

You can't ignore what they are telling you about supply though - that they can't get through to the flot, that your men are running out of bullets, basically, and will end up surrendering unless you do something. Which, for me, is the lesson in all this. When playing ANY scenario you can't just establish a strong bridgehead (or perimeter)and assume supply will go through. Supply is going to get interdicted where you are under attack by that attack itself, and if there is a much greater weight of enemy coming at you supply is going to get interdicted not just at the points of contact, but in other areas proximate to that contact, because weight of enemy firepower interdicts the supply chain behind the flot.

I've seen no evidence that something similar happens to the attacking force (it's own supply is interdicted behind it's own flot as it attacks), but it's hard to get such evidence since I don't have access to reliable accounts of the enemies supply state. But it may be that the advantage here lies with the attackers.

The question I now have is what to do about this? What tactics are an appropriate measure to keep your men in supply? If there aren't any that would work as would happen in real life, then that would be something that needs fixing, I suggest (by coding so that in an engagement supply gets through in smaller man-ported quantities - surely THAT is what happens in real life? - though I accept that sometimes conditions could be so atrocious that units just do run out of supply and can't be re-supplied because the enemy completely controls access to the flot)). Without this then your only option is to pull units right back to safety to be resupplied, but that is a bit absurd mid-engagement, no? And again, you would have to ask - if at some point you can pull your units back (and of course it's possible you won't be able to due to combat conditions)then why can't they instead provide enough suppression to let some supply through?

I would very hesitantly suggest we need one refinement (not really a fix) - that instead of losing trucks repeatedly through the AI trying to re-supply hard-pressed troops, the coding makes it so that the AI can (a) change routes better to avoid interdiction, (b)push through in certain difficult circumstances (those where we would previously have been looking at a 100% interdiction message)a smaller quantity of man-ported supply, without loss of trucks. The 100% interdiction should only occur where there is such a weight of enemy confronting the flot that it makes sense to think of the enemy completely controlling access to the flot.

[navwarcol]

Phoenix, I am thinking the same thing. I do think artillery could easily pin down the chokepoints (including a bridge) if the other side knows supplies must come over that. I think it should not cause 100% casualties though. That is the only way I can think of, to explain how it happens sometimes though. Perhaps you could run your experiment and remove all IF capable units, (and no airstrikes)?

[Phoenix100]

Did it already navwarcol, just forgot to mention - thanks. Took out all arty and air and the interdiction still occurred. It's not (only) arty firing on distant supply choke points - as I say, I'm sure it's just the front-line engagement conditions themselves. But you look at some of those red-boxed units in the picture above and it IS reasonable to suppose that they would not be able - by day, or even night - to creep supply across the polder, certainly not possible to drive jeeps across in full view of the enemy. I note that (in RL) an American soldier has just received the CMH for this very activity - re-supplying his men in extremely dangerous combat circumstances (you read his story and you see what it means for the enemy to control access to the flot). So I think the modelling is realistic enough as it goes, maybe just needs a little refinement so it really does happen only when it should. The prob - as you say - is that meanwhile we can't stop the supply attempts and hence lose the trucks. And the tactical problem is perhaps only the same prob they have in real life - what to do when you can't get supply through? But as I said above, if it is possible - by night or otherwise - to pull troops out (albeit with losses) in order to re-supply them in safety then it ought to be coded that you could instead get small man-ported quantities through. If men can get out then they can get in. But the coding at the moment assumes, I think, that all supply is by vehicle. Only where you couldn't actually move the troops out - where it was that bad - should supply be completely interdicted, I think.

[dazkaz15]

Very nice write up there mate.

I personally would like to see all the yellow 100% losses" to be turned into, red "supply could not get through" messages, until we have a version of the game that will give us more control over the supply.
Maybe the ones that say a lesser % has been lost could stay, as those messages seem to rarely happen for some reason.

[Arjuna]

Perhaps a quick fix would be to revise the way the Supply Arrival Event works. When it fires the route is rechecked and the current enemy firepower along it determined. This then is used to determine the casualties to the supply column. Currently this happens automatically. What we could do instead is add a random die roll to see if instead the column turns back before being destroyed. I don't think it realistic to always turn it back if there I some enemy firepower. Rather, we could determine the likely percentage loss and cap this to 90% and then use this probability value. That way if the likely impact is low there is a greater chance they will risk it.

[dazkaz15]

I like that suggestion, and it would work well to a degree.

It will work for enemy along the route that the AI wants to go, but that is not always the best route, and often not the one I would choose as a commander.
The other issue is that it won't stop them getting shot up from enemy you are in contact with from the front.
In my experience ammo is usually deposited at the Coy HQ which is a little way to the rear of the platoons, then distributed by the HQ staff, or collected by men form the Platoons, not the logistics guys driving right up to the front line.

I'll try to do some reading up to see how it was handled during WW2.
Like phoenix has said before though if there was ammo at the depot they would find some way to get it to the troops if they ran out of vehicles, albeit in smaller quantities.
Requisitioned vehicles and manpower from local sources, or from drawing personnel, and vehicles from the Coy's springs immediately to mind.

I cant ever imagine a well stocked supply depot not making any effort to get supplies though, if there was a valid route, or not releasing ammo directly to the Coy's that make it back to the Depot, just because they have ran out of vehicles.

It would certainly help though, and is a step in the right direction.

[Phoenix100]

That sounds like a great quick fix to me, Dave. It would mean that there was at least some chance that the calculation would take into account the likelihood of interdiction and some 'choice' would be exercised if the risk was too high.

I assume that the calculation of enemy firepower 'along the route' includes the firepower at the very end of the route, which is where - in all these 'problematic' examples - all the interdiction is actually originating. The result I would like to see is that in, say, nine out of ten instances, when the calculation determines that the enemy 'completely controls access to X part of the flot' then the column goes nowhere near that part of the flot, no trucks are lost (from interdiction at that point, whatever might happen somewhere else along the route)and you get a message saying 'H company is cut-off and cannot be supplied' or some such. That leaves how you define 'completely controls access to x'. But I would have thought some line of sight calculation combined with firepower comparison would do that (though it would be possible to argue about it, of course) - which surely is something like what the calculation does anyway, already - when it's deciding whether a certain weight of firepower does actually qualify for interdiction, no?

I can see that how to work out the other part of the issue - getting some smaller quantity of man-ported supplies through - would be much more complex. It would kick in, I would think, under circumstances where the enemy had any degree of control of access to the unit requesting supply, short of 'complete control'. Then you would simulate the jeeps stopping well away from that area (so again, no jeeps lost at that point on the supply route)and men carrying smaller amounts of supply through. Some of those men would be casualties, of course (either taken from the unit HQ, the unit itself, or the base manpower total). How much supply and how many casualties would be on a sliding scale which depended on the degree of control of access exercised by the enemy.

And wouldn't that calculation be something like this? 1. Precondion for 'control of access' - complete line of sight from some enemy unit to unit requesting supply and the area immediately around it (including behind it). No line of sight, no control (so in the last picture I posted above there would not be any control over the unit 11-HOF (with the red interdicted box showing), I think, because it's in a forest at night and it's not reasonable to assume the enemy can snipe at men creeping through that with backpacks full of ammunition). 2. If precondition 1 exists, then a sliding scale based on something or some complex of conditions, like firepower. So (i) enemy in contact with unit is 10% greater = 10% control of access = 50% of normal supply gets through by backpack, with a casualty rate of 1 man per run (or some percentage), (ii) enemy in contact with unit is 20% greater = 20% control of access = 40% of normal supply gets through by backpack, with a casualty rate of 2 men per run.....Etc Etc.

But I think you would still need a 'DO NOT SUPPLY' button, otherwise you might very quickly find that you were crippled through loss of men rather than jeeps.

is this all absurd and naïve? I'm just thinking aloud, really.

Another thought - why can't jeeps be landed on airlanding SEPs as part of resupply? Say 3 jeeps per drop?

[dazkaz15]

Not sure I like the idea of the Jeeps coming as resupply drops, as it never happened as far as I know.
But then I don't recall ever reading about an issue with running out of Jeeps for supply in the first place.
Although I do remember reading that if the Paras where dropped with more Jeeps, to carry the men in, it would have made a big difference to the overall operation as they where dropped so far from the objective.

I guess that if they did run out though, and they could get through on radio they could have requested a few gliders with some in.
After all we are talking about the entire 1st Airborne Corps becoming combat ineffective, in very short order because of not having any left.
That's a damn good reason for a Jeep resupply in my book.

[Arjuna]

In actual fact supplies are already dropped a short distance behind the unit - it is assumed that the unit sends personnel or their own vehicles to pick it up and carry it forward.