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:
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!]