We always hear the stories of the journeys to their destinations, but not how they go back. Were they still targeted by U-boats? did they sail a different return route? etc etc
Here is a map outlining the principal convoy routes. The convoys returning from the USSR- codenamed QP (1941-42) and RA (1942-end of the war) - would have largely followed a similar route home, perhaps diverging depending on conditions or a threat of attack. They were still targeted and attacked by German submarines (as well as Luftwaffe aircraft and Kriegsmarine surface warships), as convoys returning from the Soviet Union suffered a similar amount of losses as convoys heading there.
