Oscu said:No, not quite. Singapore was heavily fortified aganist naval attack, but had little or no fortifications aganist land attacks (mainly because land attack was considered impossible to carry out through the jungle).
Weaponry used in different type of fortications vary quite a lot. Coastal fortresses had huge guns that would have been of little worth aganist land targets...or atleast could be done with lighter guns. Weapon mounts, target areas, detection equipment and fire control systems are different.
AFAIK fortresses on french coast were not heavily fortified aganist land attacks and Tobruk had little in a way of coastal fortress (not sure though).
Your basic MG bunker is pretty much the same, but has little effect aganist battleships. And just the reminder of what the brits did aganist chinese in opium wars: Since their guns had longer range brits bombarded chinese fortresses to pieces (as well as their ships) and chinese could not return fire.
Ok, easy solution, if the sea province is touching a land province that is fortified then it continues the defensive line from the adjacent land province to the sea so there is no gap in the land defense line. The opium wars and WWII are a rather long time gap in technology.