Trickery and Corruption (TCG)

Note: This chapter refers to rules and concepts used in TSR'S BATTLESYSTEM™️ miniatures rules. Since siege warfare is, by its very nature, an activity involving scores, hundreds or even thousands of troops. BATTLESYSTEM™️ is the system of choice. Of course, this doesn't mean that small segments of a siege can't be roleplayed to great effect using standard AD&D® rules.
__NOTOC__
==Trickery and Corruption==
The vast majority of fortifications-typically fortified towns that fell during the Middle Ages and early Modern period did so to tactics other than standard siege warfare. In fact, almost as many European citadels were taken by bribing the castellan or suborning the governor as by any other means.
If bribery was ineffective or inappropriate, there were many other options still open. The most famous stratagem in history is the Trojan horse, but there were other tricks almost as audacious. A good example might be the city of Ypres falling to the Dutch in 1578 after a wagon containing an unusually hairy "bride" and party of "bridesmaids" broke down by arrangement at the Messines Gate.
Magic-specifically illusion offers many possibilities. Few garrisons would fail to open their castles' gates when they saw a well-armed column of "allies" approaching to reinforce them.
More unpleasant tactics were sometimes used. Some historians claim (though others deny it) that a nasty version of biological warfare was used during the Middle Ages. Certain factions introduced material that they knew to be infected with bubonic plague (the Black Death) into enemy cities, or so the story goes, believing that soon the city would fall to them without a shot being fired. The rapid spread and terrible consequences of the Black Death might imply that this tactic was somewhat more effective than originally bargained for... be difficult.
In a fantasy milieu, the viable options are wider. Unscrupulous attackers could taint a garrison's water or food supply with material carrying pathogens from virtually any form of disease. Of course, getting hold of these pathogens might Alternatively, animals-or people-infected with lycanthropy or the wasting disease carried by mummies might be introduced into the castle. The consequences for the garrison-and for anyone taking possession of the castle later-would depend on the actual disease or infectious agent used.
Because of its generally unpleasant nature, initiating biological warfare is an inherently evil act. Races of evil alignment may use it, if practical or desired: any other commander who orders its use immediately becomes evil, with all the consequences of this change. The change can be reversed by such magics as atonement, however.