It played a major role by location, being a jumping off point for the industrial might of the US. The Germans referred to the "new" form of warfare they experienced after the Normandy landings as the "material war", they had never been up against so much armaments being fielded, not even in Russia.
Prior to the imminent invasion France had been garrisoned by mostly second rate troops, the Germans withdrew Waffen SS and paratroops from the Russian front and shortly after that Army Group Center was annihilated by Operation Bagration.