Forts had prepared positions, shore facilities, and dangerous ammunition such as heated shot, but only guns facing the attacking ship could fire. Their armament had to cover several faces and possible approaches. A mobile warship could choose its angle, reposition, and concentrate a broadside against one part of the defenses. That local advantage made frigates and other station ships practical raiders against trading posts and coastal installations in the West Indies and along the coast of Africa. A fort's total gun count therefore did not determine how much fire it could bring into a ship-versus-shore engagement.
Notable Point · 4:46-6:25
Why mobile warships could overwhelm a fort's usable guns
A warship could concentrate a broadside and change position, while a fort had to distribute guns across several approaches.