[kapuhy]

While leaving task force completely unprotected is obviously not realistic and an error in AI routines, detaching a part of escort screen to stay and hunt you to exhaustion is:

"U-371 was now unlucky enough to be the first victim of an Allied submarine hunting tactic called "Swamp". This called for the area of a known or suspected U-boat to be packed with escort ships and patrol aircraft. They would then systematically and continually search the area, forcing the U-boat to remain submerged until its batteries ran out or it tried to escape on the surface. Either option was almost hopeless."