In 1940 Auschwitz as a death camp didn't exist yet. Auschwitz was bombed by 15th AF bombers coming from Italy in Aug. 1944, but they didn't target the death camp but an A.G. Faben synthetic fuel plant nearby. Auschwitz could be bombed but the Allied command, for whatever reasons, did not consider bombing the death camp or the transportation system leading to it, and thus saving Jews as worthwhile.
Jake