During World War II ports played a very central role. For all the big logistic campaigns like the increase of troops, weapons, foods etc. they needed ports as everything was shipped. Using the sea routes from France and Great Britain the allies wanted to conquer German ports in the first place. In the course of the "Battle of Supplies" the occupation of other ports like Antwerp was also important. In 1944, the allies succeeded in driving German troops out of the ports of Toulon and marseille which was called "Operation Dragoon". Now there wasn't anything that Germany could do to prevent attacks coming from France.