So, to Solidify my ideas on Settlement Defense, Mercenaries, and Militias, there are a few key points and a few key mechanics that I feel is important to let you guys know about Now so that they can be critiqued, fed back on and honed as we truly get into the mechanical importance of Advisors.
And that will start, a bit counter-intuitively, with Manpower.
Manpower in this quest is something of an abstracted number, effectively meaning ' the effort-value of working people per 100 population.' Not everyone in that 100 is working, necessarily, as it includes children, the elderly and the infirm, but that's hard to represent without going into fractions, so instead I'm going by the abstract. For every 100 people, you get 1 manpower.
As buildings are constructed and the colony is developed, Manpower will be effectively 'Locked Up' into various buildings like the Lumber Yard, Farms and Docks, meaning you will have less effective Manpower to keep constructing buildings unless you choose to 'shut down' said buildings and pull back the Manpower to spend on construction. This is also why population growth (through births and immigration) are vital, because that growing population will hopefully keep adding Free Manpower to the pool as the initial pool is sunk into the actual running of buildings.
This brings us to the Militia.
As an action, the Martial Advisor or the MC will be able to 'Raise the Militia' in the Colony's defence, though it will happen automatically (and less effectively) if an attack is allowed to hit or if an attack hits without warning.
Raising the Militia will effectively lock up the town's Manpower in the same manner as putting them to work, and automatically shut down non-essential buildings (like those outside of the walls) to increase the Manpower in the Militia.
The amount of buildings deemed 'non essential' in such a scenario will be down to a vote. Are you pulling every last man and woman capable of work into a desperate defense against a siege? Or are you taking only volunteers in off the farms to handle a few skirmishing norscans?
The amount of Manpower devoted to the Militia will raise a bonus to the colony's defense and attack rolls, up to a cap. Adding Manpower past the cap will provide no additional bonus, but it will keep the bonus at maximum for longer, with the additional Manpower acting as a 'buffer' before the bonuses start falling off.
Colonial Defense will work like any other fight in an RPG, though with 'Quadrants' of the colony's walls acting in place of party members, rolling Defense to blunt the damage of attackers while rolling attack -with the option to risk Sallying out- to reduce the number of attackers outside. Once a Quadrant loses past a certain level of health (50% and then 25%) it will be considered that attackers are slipping past and into the colony proper, with buildings in town taking damage or even being lit on fire or looted. Defenders can of course be pulled from quadrant to quadrant to refill the Manpower committed, and the defenses can even be patched up somewhat.
Mercenaries are Powerful but Expensive forces that will also give a passive bonus or active ability to use during defense scenarios, whether that is the crushing charge of Ogre Man-eaters multiplying the damage to attackers or the wall-reinforcing bulwark of Tilean Crossbows and their iron pavise, making defense rolls reduce damage that gets through by a fixed amount.
Mercenaries do not have traditional upkeep. They have expensive contracts that lock them in for a predetermined amount of months (Usually 1, 3, or 6) before you can choose to re-hire them (potentially negotiating for a lower rate) or let them go off to find greener pastures.
You can also pay a small amount more for some Mercenaries to accompany your Expeditions, granting a big bonus to marital rolls, though this will reduce the bonuses or effect of their abilities during a defense.
Addendum:
'Personal Challenges' are something the MC or Martial Advisors can take as a special action during attacks, wherein instead of commiting to the larger fight they will instead call out enemy champions and hero units, either by siccing Adventurers on them or taking to the duel themselves.