Indeed. Had he let his generals dictate strategy, the Nazis would have won the war in Europe, and the Americans would have either not gotten involved or would have sued for peace with a Nazi controlled Europe to have a buffer against the Soviet Union.
As Vaquero pointed out, when Hitler lost his nerve during the doomed British counterattack — it was made to buy time for the evacuation — he lost the opportunity to bag most of the British army in France. The British Navy would have been available, but the blow to morale, and the probable inability to defend the homeland from any German invasion, would have been a disaster for British morale. Churchill only remained as PM because literally no one else wanted the job — he was out on his ass ten weeks after victory in Europe.
And instead of the invasion of the USSR, Germany’s finishing up in North Africa would have cut off British access to Middle East oil — a blow to maintaining both the oil-burning British Navy as well as basic homefront needs — and destroyed most of what was left of the British army. That would have meant, no staging areas for an Allied return to Europe, and for the Germans, plenty of time to prepare for perhaps an eventual Barbarossa campaign.
The consequences for the Japanese would have been grim — had they gone ahead with their attacks on 12/7/41, they would have received our undivided attention, and cleaned out of the outlying islands including Okinawa perhaps two years earlier (tough to say, since US mobilization grew exponentially as it went on); invasion of the home island would have taken place, since there was no nuclear option until mid-1945.
I still think if Hitler had made it easy for the Russians to surrender, they win in a walk....All they had to do was treat Russia as they did France, and most Russians would have welcomed the Germans as liberators from Stalin.