Blocking re-enforcements

[Ghostware]

I have a question about blocking re-enforcements. I had Washington DC surrounded and about to fall. Then a ship came up the river with thousands of re-enforcements. First question is it possible to block enemy passage of the river up to the harbor of DC, and if so how do I do this, what ships are needed etc? Second question how exactly does blocking re-enforements on land work? If a region is occupied does it block passage ? Does the railroad need to be destroyed etc? Or is blocking re-enforcements not even a good tactic?

[Durk]

Blocking reinforcements is a good idea, if you can.
The problem with Washington, DC is that you likely do not have a strong enough navy to block. But you can try and maybe you will be lucky. Any sized fleet on the Potomac set to attack, orange, might block or sink the opposing force. However, they may still get through.
Land units cannot reinforce units inside a structure, but those outside always can take reinforcements. If you control the region, then they will need to march instead of railing in.

[Mickey3D]

First question is it possible to block enemy passage of the river up to the harbor of DC, and if so how do I do this, what ships are needed etc?

As explained by Durk you can put a fleet in attack mode. You can also have some artillery entrenched (level 3 or more) along the river with the bombardment order : the reinforcement won't be destroyed but can suffer important number of hits depending on the number of batteries.

Second question how exactly does blocking re-enforements on land work? If a region is occupied does it block passage ?

If your opponent has less than 5% military control in a region, he will automatically switch to offensive mode and attack any of your force in the region.

Does the railroad need to be destroyed etc?

You must have 25% military control to use the railroad in a region (even if no ennemy unit is present). So controlling a region is another way to deprive your opponent of railroad movement.

[ArmChairGeneral]

I take it you controlled the DC region, but he was besieged inside the structure? When his re-inforcements arrived, did they enter combat?

If the reinforcements had entered by land and you had full military control in the region (by winning a battle on a previous turn against the force he had in the region and forcing it to retreat) then when his force entered it would have switched to Offensive posture and engaged one of your stacks in combat. This is exactly what one would expect: if the reinforcements want to get into the structure with their friends, they will have to fight their way through the besiegers.

The situation is a little murkier when the troops are entering aboard ship via the harbor. I think I have seen something like this before: you expect the troops arriving by transport to show up in the region, thus triggering the posture switch and engaging, but instead they enter the structure directly (in this case the structure they enter is the harbor, but all structures get lumped together into one in terms of combat locations) and do not engage. I am not 100% sure exactly how this works, or that this is even what happened in your case, but I will say that in general naval transportation is tricksy with lots of strange edge-cases that can leave even experienced players scratching their heads.

Did those reinforcements show up in the structure, or in the region? If they went directly into the structure, then that is why he was able to sneak past you. If instead they entered the region without sufficient MC and still weren't forced to fight, then I am mystified.

Unlike railroads, mere possession of an unblockaded harbor (which you have if you have anyone inside the "structure") allows full use of it, regardless of MC. The only thing that denies harbors from working is a direct blockade of the harbor exit points. (A side effect of this rule means that harbors can continue to bring in supply if the path isn't blocked and there are transport points available, even though the structure is under siege and land supplies are cut off.)

Intercepting fleets or even troops-in-canoes (stacks using riverine movement orders) in water regions is not guaranteed, nor is it guaranteed that entrenched batteries will actually discover and fire upon them. Having a brig or two in a fleet will increase the Patrol value of the fleet significantly, making it better at spotting and engaging enemy ships/troops, although there is always a chance they can Evade you.

[Gray Fox]

Ghostware, was an icon present in the D.C. region (iirc it's Prince George MD) indicating a siege? I believe that with the new rules, it may be possible for both sides to have stacks in the same region and nobody control it to the exclusion of the other. The Union force would have to be in the region and not inside the city/redoubt of D.C. I asked exactly this question months ago and this may be the case.

[Ghostware]

I was confederacy with 3 large stacks in full assault mode (red) in DC region and for whatever reason the AI had most its force up north fighting my other army. When I put my curser over DC it had very little troops in it. I had attacked once and had confederate victory (not sure why it didnt fall completely, this was my first game so im learning) I was about to attack again thinking surly this round it will fall completely when during the turn I see a union fleet come up the harbor and go directly into DC with thousands of troops and I had to back off.

[Captain_Orso]

As Durk noted, the only way to stop a fleet from entering Washington harbor--with or without troops--is to intercept them and beat them in battle, in which case they will retreat into another water region and end their turn there.

The rule with MC is in 2 parts:

• A stack in a region, whether moving or not, in which its faction has <5% MC, will automatically change to OP, unless in PP.
• A faction in a region with >=5% MC will always maintain at least 5% MC.

For the inundation and siege of Washington this means that the Union can also march troops into the region without them changing to OP, which does not mean that an enemy field force will not attack them if it is in OP.

Gray, I believe the siege icon will appear even if there are defending troops in the field--a minor bug--, but you will get no siege message and a siege is not actually taking place.

Yes, the Union could also use the RivTP (Riverine Transport Pool) to move into the Washington region, and target the besieged stack in the structure-location to join that stack, but unfortunately using the RivTP does not allow such a moving stack to 'sail into the harbor', which means they actually land in the region before joining the target stack, with all the consequences of such an action.

BTW once the besieging force has >= level 3 entrenchments it can use the Bombard Passing Ships SO to stop supplies from passing through any neighboring water regions, which would prevent supplies from passing through the Potomac River region to reach Washington. Posting >= 2 naval combat elements in the Potomac River region will do the same up to 90% per Supply Distribution Phase if the supply line is crossing the Potomac River, because the Blocking River Crossings rule is capped at 90%, which means that per turn there is 3x a 10% chance of getting supplies across the river[SUP]1)[/SUP]. If the supply is moving through--as opposed to over--the Potomac River region any unopposed naval combat element or battery with the Bombard Passing Ships SO will block supplies from passing through that region.

[SUP]1)[/SUP] This rule was created to satisfy all those whining about not being able to sneak across or force a crossing over a patrolled river region. Thanks Obama!! .......................................

[ArmChairGeneral]

After some testing, I can report that everything said above is true (except the Obama part: surprisingly he is more of an EAW guy) and want to clarify some confusing things vis a vis sieges and relieving them.

If a unit enters a region via ship, it automatically arrives in the structure (since it disembarks in the harbor). If a unit enters via riverine orders, it automatically arrives in the region.

Since one side has units in the structure during a siege, then it always starts with 5% MC in the region, meaning that a friendly stack entering the region to support/reinforce it will not be forced to switch to Offensive posture. (Sometimes it will show less than 5% MC because of things that happened during the last turn, but on day 0 of the new turn, it will revert to 5%.) If you are a besieger, and you want to prevent land stacks (or riverine stacks) from entering the region without a fight, you will need to set a stack to Offensive (orange) posture to oppose it.

Quirk: from what I can see in testing, if you are besieging, and have an Offensive stack, it will begin to increase military control above 95% during the turn, but at the beginning of the next turn MC reverts to 95%. Consequently, when the enemy stack tries to sneak in while you are in Offensive, MC will have fallen below his 5% threshold when he gets there in the middle of the turn and he will switch posture, so you will usually BOTH fight in Offensive posture, rather than the reliever unnaturally being able to defend his way in (this could use more confirmation, but I saw it happen a couple of times). If you are not in Offensive posture, you do not increase MC during the turn and so a reinforcer can sneak in without triggering a battle.