Outwork
An outwork is a minor fortification built or established outside the principal fortification limits, detached or semidetached. Outworks such as ravelins, lunettes (demilunes), and caponiers to shield bastions and fortification curtains from direct battery were developed in the 16th century. Later the increasing scale of warfare and the greater resources available to the besieger accelerated this development, and systems of outworks grew increasingly elaborate and sprawling as a means of slowing the attacker's progress and making it more costly.
