There was no German shipping in the Atlantic to attack. After the Bismarck was sunk German surface ships rarely left port. In those days subs were poor at anti-submarine warfare, so there was really no need for them.
On the other hand, we were trying to do to the Japanese what the Germans had done to Anglo-American shipping, only on a more successful basis. So, we sent as many subs to the Pacific as we could.
Bump to keep Homer from crying.