A properly located fortress is an Area Denial Weapon Systems.Not even taking into account the feasibility of NBC's? (Or Area Denial Weapon Systems)?
Which meant that the firebases were too tough to take, therefore satisfying the classical definition of an effective fortification, but not really a fortress. A firebase is the next step down from a Forward Operating Base, a fortified encampment with 1 or more artillery batteries, between a company and a battalion of infantry to patrol the zone covered by the artillery, and logistical and support elements. :coffeeDid you review ANY of Americas FB's in Vietnam? They were simply bypassed and harassed