You are right, Swep but.......it was called the Transport Plan and it involved the dislocation of the railway system in north eastern France, Belgium and Holland. The allies bombed railway junctions, bridges, anywhere they could create a bottleneck to disrupt the rail system and prevent the Germans bringing in supplies, reinforcements or heavy units to face our armies in Normandy. It was successful but in the spring of '44 it cost the lives of several thousand civilians in these countries.
Large unexploded bombs used to be fairly frequently uncovered in the UK but these discoveries have become much fewer in recent years. I believe large bombs are still being dug up in parts of Germany on a weekly basis.
When I was a kid, anti-shipping mines were still being hauled up out of the coastal waters of the UK by local fishermen. If you've been for a walk along the seafront at Folkestone you might have passed one now being used as a letter box by our post office!