 On September 21, convoy HX 72 of 42 merchantmen was attacked by a pack of four U-boats, which sank eleven ships and damaged two over the course of two nights.In October, the slow convoy SC 7, with an escort of two sloops and two corvettes, was overwhelmed, losing 59% of its ships.The battle for HX 79 in the following days was in many ways worse for the escorts than for SC 7.