So we now agree that actually taking Murmansk in 1941 was impossible? Good. I'm glad that we agree on that.

Bombing Murmansk into oblivion and cutting it off with U Boats? Sure, committing more air and naval resources to those ends would have helped. But, don't forget that the USA was already supplying Britain with military assistance in 1940 AND was waging an undeclared naval war against Germany. So the Germans would have to contend with that.

Cut off Murmansk? Fine. That was not the only way the the Allies were helping the Soviets. There was the supply line through Iran to help. There was the supply line on the East Coast of the Soviet Union - Vladivostok, too. Murmansk wasn't the sole supply line to aid the Soviets.

Citing a book about how Hitler could have won WW2 is a little outside of the topic of Barbarossa. Admiral Raeder's ideas are probably not completely correct, because the Med was a theater of war in which air and naval were extremely important, especially naval. It's very clear from the historical record that the German Navy in WW2 was very small and no match for Britain. The Italian Navy in the Med was of little use.

All Axis forces in the Med were dependent on an over-the-sea supply line, and, Britain's navy could and did severely restrict that supply line.

But we can speculate on how Hitler could have won WW2. It's just that it is a bit outside of the topic of Operation Barbarossa, which is the name for the invasion of Russia in 1941, and which was intended to culminate in late summer or fall of 1941.

My own speculation on how Hitler cold have won WW2 involves long-term planning to put the German economy on a total war footing in 1939 or earlier. But, as I have said before, Hitler was not a long-term planner. Hitler fought the entire war by reacting to events with improvised methods. Hitler did not expect the World War to begin on 1 Sep 1939 when he invaded Poland. He had to improvise from the start and he never stopped improvising.

So, any speculation WRT how Hitler could have won must begin with by changing Hitler himself into something he was not. He was not a long-term planner. He reacted to events by improvising military solutions to the problems that arose from events that he did not expect.