After a careful campaign of disinformation that throws the German defenders off-guard, the Western Allies finally land on Normandy. After fierce fighting, they establish a foothold in Europe. France is liberated.
The Western Allies secure supply routes that will allow them to enter Germany, and the Ardennes counter-offensive fails. The Red Army advances rapidly, and Stalin shows uses the war for Empire-building. The SS implements the Holocaust.
The Marines succeed in the "island hopping" strategy against suicidal resistance. The US Navy establishes supremacy, cutting off Japan. Re-capturing the Phillipines and Burma is costly, but now Japan is fully in the defensive.
In 1945, Germany is crumbly on both fronts. The Western Allies cross the Rhine and take most of Germany, while the Red Army quickly advances into Berlin. After Hitler's suicide, Germany surrenders and is divided among the allied powers.
Japan continues its suicidal resistance, and invading is costly. After 2 atomic bombs, the Emperor intervenes and stops the War. Stalin grabs territory in East Asia. The War is over, and the Atomic Era and the Cold War starts.