Lorient sub pens were bombed during the war. My father had been a draftsman at Electric Boat company, Groton,Ct and was stationed on a minesweeper flotilla that operated along the French post DDay French coastal areas. While docked in Lorient he visited the sub pens and was very impressed by the facility. I remember him saying that the Germans had a concrete plant on site that repaired bomber damage to the roof before the aircraft landed back in England.