Looking through this forum, in pictures of games, I have never seen someone trying to defend occupied naval cities, and instead just leaving it to invasion. However, I usually just get corvettes and put them in occupied naval cities to defend. When I annex a naval city, I treat it like homeland and use stronger naval units to defend, which is another thing. I don't see anyone leaving ships in cities, but spreading them around the ocean. What if someone attacks you, and easily takes your homeland cities and capital? Am I not understanding something?
All Shall Eventually Fall