Of course there’s always France, which is friendly territory, but it is a siren whose allure must be sternly resisted. It’s not enough for Bischoff just to run the U-boat aground on a godforsaken beach somewhere; he wants to get the thing back to a proper base. But the skies above the proper bases are infested with Catalinas, illuminating the sea with the satanic light of their radars. It is much cleverer to make them think that he’s headed for France, and then head for a German port instead.