German destroyer range and the problem of reaching the Atlantic

Prewar German planning could not assume access to French and Norwegian bases. Ships intended for Atlantic operations would have to fight their way out through the North Sea, then retain enough endurance to operate and return. Meeting that demand could push a destroyer toward the size and requirements of a cruiser. One proposed response is to build cruisers for distant operations and torpedo boats for local work. That choice would leave Germany short of destroyers once unexpected conquests opened new operating bases, but those opportunities were not a sound starting assumption for the earlier design programme.