The sinking positions cluster in a limited area around 56 degrees north and 10 degrees west. Many boats had their hatches left open before surface ships fired on them. Accounts include accurate four-inch shellfire and the use of pom-poms against the target hulls. In one example, a parted tow forced the Polish destroyer to sink its submarine with every gun available.
Notable Point · 1:24:14-1:26:05
Naval gunfire and parted tows in U-boat disposal
Boats prepared to flood were sunk with naval gunfire, while a parted tow could force an escort to use every available gun.