Inspired by the Book of Battle, I've put together a little system for running sieges with a bit more detail than what's presented in the core book/GPC:

(A quick caveat: these rules have not been playtested--although they certainly will in upcoming sessions of my Solo Great Pendragon Campaign--so feel free to tweak and adjust the table and results as you see fit. Feedback's always appreciated!)

Pendragon Siege Table

At the start of the siege, the GM determines the Siege Intensity, which should range between 20 for sieges involving a couple hundred knights total to 30 for huge sieges involving thousands of knights on a side (Joyous Garde, for example).

The GM should also name a Time Interval: one day, one week, or one month. TI should be based on strength and provisioning of defender's position; figure a TI of a day for defenders in an exceptionally weak position or who were caught by surprise, a week for average preparation and defenses, and a month for exceptional preparation and defenses.

Figure DV modifiers as usual. Additional modifiers from p. 15 of the Book of Battle may be applied if the GM wishes.

Both Defender and Attacker roll Siege skill once per Time Interval. One opposed roll constitutes one Time Interval. Consult the Siege Table for results and add or subtract from the intensity.

If the intensity dips below 0, the attackers lift the siege and go home.
If the intensity rises above 40, the defenders surrender automatically.

At the GM's whim or as determined by a Siege Table result, selected Time Intervals can feature "extended resolution" phases in which the PCs are allowed to take action (lead or beat back an assault, attempt to sneak into the fortress, lead a sortie, etc.). These extended resolutions should trump any other considerations of intensity level or programmed results.


Attacker
DefenderFUMBLEFAILURESUCCESSCRITICAL
CRITICALReliefDesertionCountermeasuresNothing
SUCCESSDisease (A)SortieNothing (Disease - D)Siegecraft
FAILUREStarvation (A)Nothing (Disease - A&D)AssaultDisease (D)
FUMBLENothing (Disease - A)Starvation (D)TraitorWall Breach

"A" - Attacker; the besieging force
"D" - Defender; the force under siege

(A slightly more legible version of the above table is over at my blog: http://shirosrpg.blogspot.com/2010/04/pendragon-siege-rules.html.)

Definition of Terms

Assault: Both sides make an opposed Battle roll; defenders add the unmodified Defensive Value of their fortification unless there's been a Wall Breach result in a previous TI. Both sides then consult the Follower's Fate table in the main rulebook to determine casualties. Additionally, if the attacker succeeded and the defender failed, Intensity is raised by 10. Likewise, if the defender succeeded and the attacker failed, Intensity is lowered by 10. Criticals or partial successes have no further effect.

Countermeasures: Although largely confined to a passive role, there were options available to defenders--counter-mining, counter-battery fire, psychological warfare--that allowed them to take action from time to time. These countermeasures are abstracted, represented by applying a -2 to Intensity.

Desertion: Dissent and boredom in the besieger's ranks leads to mass desertion. Lower Intensity by 1d6+4.

Disease: Sieges inevitably became charnel pits of festering disease for attacker and defender alike. If the attacker is afflicted with disease this TI, lower Intensity by 1d6+4. Likewise, if the defender suffers an outbreak, Intensity is raised by 1d6+4. Note that these results can cancel each other out if both attacker and defender suffer from disease in a single TI!

Relief: The fervent prayer of any besieged force was to see a friendly army approaching from over the horizon. Such an event imposes an immediate modifier of -20 to Intensity; if this drops the Intensity below 0, the besieging army withdraws automatically in the face of the approaching relief force. If Intensity is still above 0, the GM should run a battle using the Book of Battle to determine the victor. If the PCs are part of the besieged force, they may of course elect to lead the defenders onto the field of battle and fight alongside the relief force.

Siegecraft: The machinations of the siege engineer are particularly effective this TI. Perhaps a well-placed hit from a trebuchet brings down a tower, or a mining operation makes particularly efficient progress. The particulars are abstracted, and are represented by applying a +2 to Intensity.

Sortie: Besieged knights, always on the lookout for opportunities to put their martial skills to good use, spot a perfect moment to strike and ride out in a sortie intended to sow chaos, death, and confusion among the besieger's camp. This can be played out as an extended resolution, or resolved simply with opposed Battle rolls. Casualties and Intensity adjustment are figured as per Assault, but Intensity is only modified by +/-5.

Starvation: The bane of the defender, and the most common way to bring sieges to an end, starvation could affect attackers as well if the camp quartermaster did not make adequate preparations--an army camped in a single location for an extended period of time will quickly use up all the local resources. If the defender rolls a Starvation result, add 5 to Intensity; likewise, if the attacker suffers Starvation this TI, subtract 5 from Intensity.

Traitor: Aside from starvation, most sieges were ended not through bloody assault but by treachery from within. A Traitor result grants the attacker his choice of: (1) an immediate +15 to Intensity; or, (2) a reflexive modifier of +10/-10 on his next Siege roll (in which case a result of Wall Breach represents the Traitor opening the gates from within).

Wall Breach: Through battering ram, mining, trebuchet, or treachery, a wall or gate has been breached and the besieging force pours through. Add 20 to Intensity; if the modified Intensity is 40 or above, the defending garrison capitulates and the besieged residents are at the attackers' mercy. If Intensity is still below 40, the GM should run a skirmish to determine the fate of the PCs (barring some extraordinary heroics on the part of defending PCs, the besieged residents are still doomed; the skirmish merely determines how the PCs and their followers fare in the chaotic fighting through baileys, streets, and corridors).

It all looks very good! The only thing that is unclear to me is the TI. Since it seems arbitrary to a point anyway, i would simply roll a # of random d6 and each succcess is a day, or EVEN BETTER.. I would just let the GM set the time based on story guidelines. If neither is acceptable then maybe just come up with a more detailed formula for why the TI is what it is? Provisions vs, other considerations, etc... ( i dont know what specifics u might use here). But at the core i like what you have done with this . Thanx :)

It all looks very good! The only thing that is unclear to me is the TI. Since it seems arbitrary to a point anyway, i would simply roll a # of random d6 and each succcess is a day, or EVEN BETTER.. I would just let the GM set the time based on story guidelines. If neither is acceptable then maybe just come up with a more detailed formula for why the TI is what it is? Provisions vs, other considerations, etc... ( i dont know what specifics u might use here). But at the core i like what you have done with this . Thanx :)


Sieges from history tell us they can take weeks, months. So, I think I have to agree is agreement about what fits the story line. But, for small scale stuff (e.g., the raiders coming in and finding no resistance whatsoever, might try a small siege to the manor to see if they can get the good stuff) marking days might be a good measure.

Bob

Well its all ver good. :)

Sirlarkins - I've used these rules a bit now and I wanted to share my feedback and raise some points.

Firstly, your table has no outcome for partial successes. If you have two commanders, each with a skill of 20, both of them will always succeed. This means that as it stands only the 4 top right options will ever be available. I would suggest the addition of a TIE/FAIL and TIE/WIN outcome (as with the Harvest table in BotM for eg). I haven't thought long enough about what those results should be but something that sits between the current options would be suitable.

You say "Figure DV values as normal" but what is the effect of DV on the outcome? From your list I only see DV being used when an Assault is called, but - as mentioned above - an assault will never be called when two good siege commanders face one another. Have you tried adding DV to the defender's Siege skill or using it as a modifier to intensity? For what it's worth, I've tried both ways and the former is far more potent. Even in a simple motte and bailey the DV of 8 makes for a sizable bonus. Adding it to Intensity is more balanced but it also creates odd results. For example, if you have a large siege, against a stone castle, the modifiers will cause the besiegers to give up the moment they arrive :)

With regard to Intensity, this is not being used in the same way it is in BoB. Here we have Siege skill vs Siege skill whereas vanilla BoB pits Battle skill vs UI. I'm sure this was intentional on your part I'm just making the observation. Part of the outcome of this is that, unless I'm missing something, the rise and fall of intensity has no effect on the progression of the siege until the very end. However, if you use Intensity instead of Siege the skill itself becomes somewhat redundant, especially when a PK is doing the defending.

For discussion purposes I thought of using Siege to determine the level of protection that the fortification provides, similar to that suggested in BoTM. So a knight rolls his siege skill and the outcome determines the DV (whether total or a fraction of) to be used for that round or TI. The siege itself could then progress vs Intensity without negating the use of the Siege skill.

Anyhow I like what you've done here, and none of my suggestions have been rigorously playtested. I just fudged the outcome based on your table, my own gut instinct and some assaults using the Attack vs Position maneuver from BoB.

Hello everyone,

I was searching into the forum for hints about how to manage a siege situation... and... voillaz!!! I found this wonderful piece of mind!!!

All to say I find it wonderful, just I finished reading the web page you linked, then determined what I think to have understood, and finally I find the feedback of Sir Pramalot.

Whoa!!!
I'm a bit confused.
If you are still somewhere around, could you post some example? Perhaps that may make the matter clearer to my poor mind.

Thank you all!!!