Bastion

A projecting part of a fortification, typically with two faces and two flanks, designed to provide defensive fire along adjacent walls.

Bastion trace: The geometric plan of a bastion and its connections to the adjoining fortification walls. Its faces and flanks define the angles from which the bastion could cover nearby defenses.
Trace italienne: A system of low, thick, angular fortifications developed in Italy during the early modern period. The bastion became the defining element of this artillery-resistant design.
Vauban: A French military engineer who designed and improved fortifications under Louis XIV. His fortified towns refined the use of bastions within a coordinated system of defensive works.
Fortress city: A city whose layout and development are strongly shaped by permanent defensive fortifications. Bastioned ramparts constrained urban expansion and organized movement through fortified gates.
Curtain wall: The section of a defensive wall connecting two towers or bastions. Bastion flanks swept the ground immediately in front of this otherwise vulnerable wall.
Medieval fortification: Fortified structures and defensive systems used in Europe during the Middle Ages. Tall medieval walls were vulnerable to cannon fire, prompting the shift toward low bastioned defenses.
Siege of Maastricht (1673): A 1673 siege in which French forces under Louis XIV captured the Dutch-held city of Maastricht. Vauban’s siege approaches targeted the bastioned defenses protecting the city.
Star fort: A fortification with an angular, star-like outline formed by projecting points and recessed walls. The familiar star outline results from arranging bastions around a fortified enclosure.
Flanking fire: Fire directed along the length of a defensive line or across an approach rather than straight ahead. Bastions were positioned to deliver it along adjacent walls and their approaches.
Gunpowder warfare: Warfare shaped by the use of gunpowder weapons, including artillery and firearms. Increasingly powerful cannon drove the redesign of fortifications around bastions.

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