A major concern to Dönitz was Operation Overlord, the long predicted landing in France, and what role the U-boat arm and surface forces could play in the defence. He was sensitive to a landing on the Bay of Biscay but retained boats there only for operational readiness. Dönitz ended reconnaissance operations in the region. In the BdU war diary he wrote of ending operations since "otherwise the strong enemy air activity will lead to high losses which would only be acceptable if an immediate landing on the Biscay coast were expected. As this is no longer considered an acute danger the boats will remain at readiness in the concrete shelters."