Newbie Tactics

[Chazar]

One should also recall that any losses to PD are for free, since PD is only decreased by loosing the entire province. So buying some PD in order to have some upkeep free meat shields might be sensible for some provinces which need to be defended often against weaker armies like those sent by the AI.

However, the PD must be backed up by mages and maybe some archers or other better troops in order to successfully defend a province from any attack. So before your "PD-mages" get bored, one might consider building a lab to keep those mages occupied, while they are still defending the province.

However, once you decide to forify even further by building a fortress, the PD rather becomes a liabilty: the researching mages will not fight anymore alongside the PD in a fortified province, so the PD will be lost to an attack without further protection by mages. Thus it is usually a bad idea to buy PD.