During World War II, the occupying Nazis understood that if the Allies wanted to retake France they’d have to land troops and a port would provide the logical place to put heavy equipment and supplies ashore. So they fortified Cherbourg and other channel ports to make them hard to capture.
The allies responded to this obstacle by putting everything ashore at a portable port they created on the Normandy D-Day beaches. They created a breakwater by sinking old ships and special towed huge concrete boxes called “mulberries” of which you can still see some remnants. The D-Day landing remains one of the largest and most complicated human undertakings ever attempted within the span of a few days.
The Nazis in Cherbourg were surrounded and cut-off but Hitler ordered them to die where they stood. They held out for weeks of intense fighting and destroyed most of the port facilities.
I wonder if any remnants of that fight remain? Probably not much. We think of Normandy as a historical battlefield but the inhabitants think of it as home and, naturally, don’t want it left in a shot-up, blown-up condition. They have lives to be getting on with; they aren’t docents in a Williamsburg-style tableau.