What are you talking about? Gdansk is a main seaport on the Baltic Sea, which is not a constrained passage. There is no "rat maze." If you are willing to accept sea transport to Germany, there is nothing else to worry about when traveling a few more miles to Gdansk (the former German Danzig). After that, conventional rail transport is more than adequate to convey military equipment. I don't understand your capitalization and exclamation points. Consult a map, for heaven's sake.

As for "vulnerable," there is no other word for cargo ships, which has been a known fact for hundreds of years. There is no such thing as "quick escape," as cargo ships are not "quick."

How old are you? I guess you have no idea how much military materiel and personnel were transported exclusively by ship in World War II. Often as closely as possible to where combat was taking place. No railroads across the Atlantic Ocean to North Africa. No railroads to Sicily and mainland Italy. No railroads across the Mediterranean Sea, Red Sea, Persian Gulf, or Indian Ocean. No railroads to the beaches at Normandy. No railroads to Brussels, after the beachhead was established. Not to mention no railroads across the Pacific Ocean. My father was in the Navy Armed Guard manning the convoys, all through the war. They went everywhere. What you are talking about would be dismissed as nonsense.