How did bastions provide flanking fire along curtain walls?

In the context of fortification, a bastion is a projecting structure consisting of two faces and two flanks that terminate in a salient angle. This design was essential for eliminating "dead space"—the vulnerable areas at the base of walls where attackers could otherwise hide from defensive fire.12

By projecting outward from the main fortress wall, bastions allowed defenders to maintain uninterrupted fields of view and fire along the curtain walls that connected them. The flanks of the bastion were specifically positioned to provide flanking fire, which swept the face of the adjacent curtain wall and the front of neighboring bastions. This geometric arrangement ensured that any enemy attempting to approach or scale the wall would be exposed to direct defensive fire from the bastion's batteries, which could be mounted along its straight, polygonal parapets.12