Given that the German Navy was not ready for war when Hitler invaded Poland, the best strategy would have closely followed what historically happened. The U-Boat campaign was very effective until the Greenland air gap was closed and an effective convoy and escort system was implemented.

The fact that enormous allied resources were tied up by the Allies in trying to keep the Tirpitz bottled up, the Scharnhorst, Gneisnau, Hipper, and others in check, it would seem that a this tactic was even more effective than direct confrontation. This division of allied air and naval forces was the most effective means that the German navy had for effectively dealing with the numerically superior Allies.

It the Germans had and used more U-Boats, particularly longer-ranged schnorkel-equipped types, and had more of the fast battle cruiser type of task groups early in the war, they could have stretched the Allies' resources and ability to supply England to the breaking point. Of course, this would have required the cooperation of the Luftwaffe, something that would have been impossible with Goering at the head.

tom