As most know, Eisenhower became the Supreme Allied Commander of all Allied forces in northwestern Europe during and after Operation Overlord. This position was highly coveted by Montgomery, who believed the position should have been his. The question is this, what would the war in France (and northwestern Europe) look like if for some reason Eisenhower did not become SAC, and instead Montgomery took the position?
Because such a POD for this would probably be very tedious at best, this is just a question as to the results of such a switch instead of how such a switch could take place.