Germans were going to lose before Stalingrad: they were fighting Russia, Britain, and the United States
With Stalingrad’s capture would mean the Germans hold the key to the Caucasus oil fields, bolstering their forces. Yes, they were doomed since they were repelled at the gates of Moscow, but if the Germans won Stalingrad, the Soviets would probably have lost a lot more soldiers than they did. Also, the loss of Stalingrad would be a huge blow to Soviet morale. Stalingrad resulted in the destruction of the German 6th Army, which left a gaping hole in the Wehrmacht, much more devastating to the German armed forces than the Battle of Britain.
Japanese were going to lose even if they completely decimated America at Midway. there’s an essay showing that American carrier numbers would overtake Japanese carrier numbers by 1943.
One essay in a sea of countless other essays. We will never know if the Japanese still could have won, but it’s still certain that Midway was the first major defeat the Imperial Navy suffered in over three centuries.
By Kursk, Germans were already losing
But, again, it was decisive. If the Wehrmacht had one the Germans would have re-gained the strategic offensive, even if it would be temporary.
Germans were definetly losing by D-Day. I never got why it was seen as a turning point.
Losing? They locked down the Allies in Italy, whom didn’t make any significant advances until well after D-Day, and if there wasn’t a Allied threat to invade from the West, Hitler could have sent much needed forces East. It was a turning point because the Allies were able to get a significant foothold in Europe, and fulfill their promise to Stalin to open up a second front in France. Hitler now had to commit significant forces on not just one major front and a minor one (Italy), he now had to deal with two major fronts and one minor one.
Even if the Soviets won and got to Berlin, say the Allies were still trapped in Italy. Who is to say the Soviet tanks wouldn’t simply continue to roll all the way to Amsterdam, Paris? If the Allies hadn’t invaded Normandy or their invasion failed, Europe would be very, very different–-and very, very red.
Japanese were already losing before Leyte gulf
Irregardless, Leyte Gulf sped up their defeat considerably. If there wasn’t a Leyte Gulf the Japanese would have caused much more casualties to the Allies.
Plus, Leyte Gulf was the largest naval battle in history. I think I’d call that decisive.