So how did the Allies get from the beaches of Normandy to Germany in less than a year? Largely by overwhelming the Wehrmacht with lots of good soldiers and practical war materiel. If German tanks, mines, machine guns and artillery were superbly crafted, more utilitarian American counterparts were good enough -- and about 10 times as numerous. Mechanically intricate German Tiger and Panther tanks could usually knock out durable American Sherman tanks, but the Americans produced almost 50,000 of the latter, and the Germans less than 8,000 of the former.
Over Normandy, British and American fighter aircraft were not only as good or better than German models but were far more numerous. By mid-1944, Germany had produced almost no four-engine bombers. The British and Americans built almost 50,000 that by 1944 were systematically leveling German cities.
Winston Churchill and Franklin Roosevelt were far more pragmatic supreme commanders than the increasingly delusional and sick Adolf Hitler. American war planners such as George Marshall, Dwight Eisenhower and Alan Brooke understood grand strategy better than the more experienced German chief of staff. Allied field generals such as George S. Patton and Bernard Montgomery were comparable to German legends like Gerd von Rundstedt or Erwin Rommel, who were worn out by 1944.
The German soldier was the more disciplined, experienced, armed and deadly warrior of World War II. But his cause was bad, and by 1944 his enemies were far more numerous and far better supplied. No soldiers fought better on their home soil than did the Russians, and none more resourcefully abroad than the British Tommy and the American G.I., when bolstered by ample air, armor and artillery support.
Omaha Beach to central Germany was about the same distance as the Russian Front to Berlin. But the Western Allies covered the same approximate ground in about a quarter of the time as had the beleaguered Russians.
D-Day ushered in the end of the Third Reich. It was the most brilliantly conducted invasion in military history, and probably no one but a unique generation of British, Canadians and Americans could have pulled it off.