While Adolf Hitler was an extraordinarily effective military leader, he was soundly defeated by the combined Allied forces in World War II. Flaws in his personality and decision making led to more than a few mistakes, which ultimately caused the Third Reich to fail.
Like many great leaders, Hitler was confident in his strategies and the abilities of his fighting force. But his ego sometimes prevented him from taking a strategic retreat when circumstances dictated it; made him vulnerable to false intelligence; and had him underestimating his opponent’s resolve. At Operation Barbarossa, his general advised Hitler that a retreat until Spring would be the wisest option as winter began to set in. But Hitler told his forces to stay put–and as they waited for the roads to freeze so tanks could continue, the Russians built up an impregnable defense against the Germans, who were by the time they arrived underclothed and underfed. the Allies issued false intelligence about which beaches they would invade as they prepared for Normandy; believing it, Nazi troops were scattered, and some beach fronts saw little fighting whatsoever. And at Stalingrad, he could not believe Slavs would be able to create a guerilla fighting effort as they did, eventually trapping the Germans inside the field of battle.
Hitler also overextended his forces, believing that they could take any territory due to their speed and force, as they had so quickly invaded Belgium and the Netherlands. But when he breached his treaty with Russia, he created two fronts, diluting his resources and power. And he overstretched his supply lines, believing that the “conquered” territories like Ukraine would indefinitely feed and clothe his troops–completely forgetting that a retreat is often much harder, supply-line wise than an invasion.
Last, but not insignificantly, his anti-semitism and racism cost him intellectual capital and moral grounding. This cannot be underestimated. By marginalizing and killing Jews and intellectuals, he threw away potential technological innoventions and designs which would have given him a further edge in the war. It was a Jewish scientist who developed the Atom bomb which brought Japan to surrender. And Japan which didn’t have a similar program against its intellectuals, had a state-of-the-art airplane. And even through Europe was demoralized, many had not lost their Christian values, and were thus appalled at the Third Reich’s racism. In fact, one of Hitler’s commanders who was a devout Catholic, von Stauffenberg, recognized this eveil and attempted to assassinate him. While this failed, it was almost certainly a harsh psychological blow to a man who considered himself a near-god.
Hitler’s mistakes reinforce classical ideas about leadership that have been around since classical Greek times., when a frequent theme was hubris. A great leader should be confident and inhesitant, indeed; but he should also be humble. Your own people and your opponents are smart & wily, too–and you need to respect that, which Hitler failed to do.