The construction of warships through the mid-1930s was primarily directed against the perceived French threat.[13] Any hypothetical U-boats would generally support the main fleet rather than embark on a commerce-raiding campaign, and any raiding would be done strictly according to cruiser rules.[14] This view remained the established orthodoxy until the mid-1930s, when then-Kapitän zur See (Captain at Sea) Karl Dönitz came to command the U-boat arm.[15] Dönitz advocated a return to unrestricted submarine warfare and the adoption of wolfpack tactics to overwhelm convoy defenses.[16]