Dominions 3: The Awakening/Provincial Defense

Provincial Defense
Provincial Defense (PD) refers to the amount of extra "garrison" troops friendly to the controlling player present in a province. During combat, these extra troops are automatically deployed in the middle of the battlefield (in addition to any normal hired units or commanders) and set to Attack/Fire Closest. PD costs no upkeep, and is fully restored after a battle if the owner does not lose control of the province.

Raising provincial defense costs an amount of gold equivalent to the new level purchased. (Thus, level 1 costs 1 gold, going from level 1 to level 2 costs 2 gold, going from level 10 to level 11 costs 11 gold, and so on.) Additional benefits are gained at levels 1, 10, and 20:
 *  1+ gain 1 Commander + 1 Archer and 0.5 Militia per point of PD. Note that some nations with unarmored troops gain 2x as many Militia.
 * 10+ auto-patrol province for hidden units.
 * 20+ gain 1 Priest + 0.5 Soldiers per point of PD.

The weakest unit/commander from each type is used, depending on your national troop choices. Thus actual PD number and composition changes dramatically from nation to nation. For example, Ulm's PD is all heavy troopers, since even it's "weakest" units wear armor, while Matchaka's PD gains extra numbers since they have unarmored militia troops wielding shields. Abyssia's PD won't include archers, since they don't have any national archer units.

Land-based nations cannot buy PD in underwater provinces and vice-versa.

Provincial defense levels cannot be voluntarily reduced once bought, but losing control of the province (regardless of the presence of friendly fortifications) resets PD to 0.

Strategies
The best way to get the most from PD will vary from nation to nation. However, it can be generalized that all PD is defensive in nature and have some intrinsic characteristics in common regardless:
 * Advantages:
 * Buying PD does not consume production resources.
 * At strengths < 40, buying PD is generally cheaper unit-for-unit than training a like number of "normal" units.
 * No upkeep nor supply required.
 * Refreshes to full strength for every battle, regardless of previous casualties/afflictions accrued.
 * Disadvantages:
 * PD never leaves the province once purchased
 * Units auto-attack en-masse and cannot be scripted nor re-positioned.
 * Generally composed of your nations weakest units.
 * If you lose the province, regardless of reason, you lose your gold investment.


 * Strength
 * Buying at least 1 PD in every province is recommended, since even if you lose the province you gain important intel via a battle report that allows you to see the exact composition of the conquering army.
 * Buying at least 10 PD in a province provides a minimum protection vs stealthy enemies. Note that increasing PD above 10, as well as setting additional "normal" flying or cavalry units to Patrol dramatically boosts the effectiveness of patrolling.
 * Buying at least 20 PD in a province gives you the best military bang-for-your-buck, since you get the full compliment of militia/soldiers/archers available for your nation and a Priest as well.

While strictly speaking PD is defensive in nature, nonetheless it can play a role while on the strategic offensive. Buying PD allows you to instantly create "garrison" troops in freshly conquered territory, while your main army moves on to conquer new lands at full strength. This can make it much more difficult for the enemy to retake their lost provinces.

Nations with expensive or production-heavy troops will find buying PD a cost-effective means of boosting their border defenses in key provinces. Strong PD can be employed in the main battle line as a central pillar of a defensive strategy, while other nations may prefer to use PD as arrow magnets or decoys to distract enemies from targeting their mages while stronger "hired" troops flank their targets. Even weak PD might be turned into an effective fighting force using the right magic.

Whether or not PD is effective depends largely on what it is expected to fight. Investing heavily in PD may make sense early on in the game to quickly establish defensible borders, perhaps even into the mid-game so as to discourage enemy assassin-, thug- or remote-ritual attacks. But if the enemy employs stealth-armies or flying SC or mass thug attacks, it would be wise to reinforce your PD with thugs/mages of your own. Since it is unlikely that any nation can afford to deploy mages to all of it's provinces, it becomes an issue of prioritizing which provinces to defend properly, and which to let go.