Napoleonic & ECW wargaming, with a load of old Hooptedoodle on this & that

Wednesday, 9 May 2012

Solo Campaign - Siege Rule Tweaks

Since it looks as though my campaign may produce a siege quite soon, I was encouraged to go back to my mathematical siege rules, since there were some bits in there I wasn't sure about. There was a post on this system a few months ago - I explained there that, though an algorithmic system for sieges is certainly not a big attraction from visual and fun-generation aspects, it is (sadly) necessary to handle sieges in this way in a map campaign, since a siege will last for a number of campaign moves (and thus must be able to coexist with armies marching and fighting elsewhere on the map in a different timescale) and also since it might be necessary to have more than one siege running concurrently.

The particular bit I wasn't happy about was the section on Storming. Without getting too deeply into the nuts and bolts (again), the idea is that the defenders have a couple of numbers associated with them - a Fortress Value (FV), which represents the strength of the place and its guns, and a Garrison Value (GV) which indicates the fighting capability of the guys in the fort - this is a kind of lumpy amalgam of numerical strength, attitude, and their current ability to carry on - for whatever reason. Similarly, the besieging force have a Battering Value (BV), which is a measure of their heavy artillery capability, and an Assault Value (AV), which is the amount of force they could bring to bear in the event of (you guessed) an assault, but this number also makes allowance for the men who are available for digging ditches, carrying stuff and just constituting a threat.

The detail of the siege rules is set out in the orginal notes, here and here, so I won't go through all that again, but the idea is that bombardment and (implied) sorties and mining etc wear down these numbers. At the point that a storm is attempted, the appropriate section of the rules is set out in its new form below, with the odd explanatory annotation here and there. The inclusion of a dice roll for the defenders and the besiegers is intended to reflect performance and luck on the day. The calculation of losses bothered me - something struck me as counter-intuitive. If the totals for ASS and DSS (as described below) were very close - in other words, if the result of the storm was a close call the casualties would tend to be relatively light, which intuitively seemed completely wrong. A close-fought storm might have the heaviest casualty rates of all, so I've made a couple of changes - I now use the absolute values of DSS and ASS, rather than the difference between them, when calculating loss, and have changed the formulae slightly. It's a minor tweak really, but I'm a bit more comfortable about how it works now. In a campaign, losses have a lasting significance.

Here's the revised section from my Campaign Rules:

11.3.3 Storming:
Defenders’ Storm Strength, DSS = FV + GV + 1D6
Attackers’ Storm Strength , ASS = AV + 1D6  [BV, the Battering Value, does not count in a storm]

* If ASS > DSS then the fortress falls and the garrison surrenders. Attackers lose a final, further 0.25 x DSS (rounded to nearer whole number) from AV. Defenders lose 0.5 x ASS from GV.
* Otherwise, if ASS <= DSS, storm is repulsed; attackers lose 0.5 x DSS from AV; defenders lose 0.125 x ASS from GV
[Losses in GV and AV are not simply casualties – they represent all manner of loss of ability to continue – and note that GV and AV can become negative].

Whenever it is necessary, at any moment during the siege (or when the siege is broken off or completed), actual casualties may be computed as one tenth of the %age loss of AV or GV since the start of the siege. 

Example – if a successful besieging force started out with AV = 8, and end with AV of 6, then they have lost one tenth of 25% = 2.5% of the total force present; if the defenders started out with a GV of 5 and end with GV = -1 then casualties are 1/10 of 120% = 12%; if the fort surrenders, the remaining 88% will become prisoners.

[It occurs to me that if I don't actually get to a siege in the campaign then it doesn't really matter that I've improved the rule, but it's the principle of the thing!]


  1. In principle this is better than the first one now that you mention it. However, a couple of thoughts come to mind.

    1. Having a larger force always taking more casualties may not feel right, especially if present in over whelming force. Perhaps allow the attacker to commit a certain proportion to the assault and only assess casualties on those?

    2. If the garrison loses to a storm, wouldn't their losses normally be 100% unless they have managed to withdraw into a citadel?

    3. What about French attacking a Spanish garrison willing to fight in the streets?

    4. Does it follow that a success will always have lighter losses? Perhaps one assault failed because it was called off early while another suceeded because it was renewed after a bloody repulse? Perhaps the % loss such be variable with one scale for defeat and another for victory to account for assaults which are less or more bloody than expected regardless of win or lose?

    I mean as long as I'm not doing the work of calculating all this.


    1. Hi Ross - good thoughts - thanks, as ever. I'll use your numbering for reference:

      (1) Agree. This is deliberately rough-&-ready - I was trying to avoid making the operations of the siege too hands-on - just sort of let the thing take care of itself, but it would be possible to nominate an assault by only a part of AV - bearing in mind that limiting the assault reduces the chances of success - yes, this is crude!

      (2) Defeated garrison do lose everyone, calculation gives killed & wounded, everyone else is captured - only has significance (maybe) in a campaign, and for sad people like me who like to have numbers to record.

      (3) As my rules stand, extra determination would appear only implicitly in a high dice roll - maybe simplest way to do this would be to have a defender bonus which only counts in a storm and gets added to the dice for certain troops. That seems easy enough to do - I'm wondering whether the guys that are crazy enough to fight for each house are also the same days who on bad days might just give up without warning. Hmmm.

      (4) Maybe the results should follow a table, similar to the Duckenfield-based system I adopted for off-table combats. I'll think further about this.