Part 62: Q&A - December 1
Empire Total War: The Second 80 Years War quick online Q&A
Q: What did nations use for coastal defenses? Did they exist?
A: There were coastal fortifications during the 1700s, however they were essentially never attacked from the sea. Basically small castles overlooking the sea, coastal defenses in the 1700s consisted almost entirely of tall towers and thick walls with very heavy cannon firing heated shot, which could light ships on fire, or detonate their powder stores. Navies didn't use heated shot until the 1800s due to the danger of using heating fires or furnaces around powder charges on moving vessels. Their sturdy nature made it essentially impossible for fleets to engage, and as they were static, fleet commanders simply never assailed them by sea.
The primary purpose of the coastal defenses were to stop enemy fleets from bombarding important coastal cities, and due to their presence, coastal ports that would otherwise be exposed to ship board cannon fire were safe from bombardment. Also, a navy could run into a port city and be defended by their fortifications at shore, making a navy in port impossible to assault by sea. For example, the fortifications around Le Havre made it impossible for the superior channel fleet of the British to attack and capture the outnumbered Dutch third rates.