I just saw an interview that was done back in the ‘70s with Karl Doenitz. He said that he had asked for more Uboats during late 39 and 40. He told Hitler at that time that with more Uboats that he could force Britain to capitulate by cutting off the supplies they were receiving from the U.S. by convoy. He said that Hitler’s obsession with building a grandiose surface navy with large imposing battleships kept them from being able to finish off Great Britain when it was most vulnerable because Hitler was unwilling to build a large number of the relatively more inexpensive Uboats to finish the job on GB.
WW2 would likely have turned out a lot differently if Hitler had not been such a stubborn loon.
Hitler was Austrian and he spoke Austrian. Therefore when he gave orders to Germans, who only spoke German, they couldn't understand him. Plus, Hitler had asthma but nobody could find a breathalyzer. That's why the war was lost.