What we are after is who, if anybody, was responsible for a clear majority of the total effective engagement of Axis forces.

On that question, it is dead clear that the Soviets were, and by a huge margin.

Did US and British troops contribute? Yes. Did P-51s and P-38s help clear the skies of effective German air power? Sure. Would the outcome have been notably different without them? Probably not.

The biggest single setback for Germany, driving deep into original German territory, happened while the US and Britain were pinned down in Belgium and Southern France by a tiny fraction of German assets. Without, the war might have gone on for up to another year, and the Soviets would have ended up owning all of Europe and, probably, Africa. We must be satisfied that that did not happen.