Article: A major problem in the managing of the Luftwaffe was Hermann Göring. Hitler believed the Luftwaffe was "the most effective strategic weapon", and in reply to repeated requests from the Kriegsmarine for control over aircraft insisted, "We should never have been able to hold our own in this war if we had not had an undivided Luftwaffe". Such principles made it much harder to integrate the air force into the overall strategy and produced in Göring a jealous and damaging defence of his "empire" while removing Hitler voluntarily from the systematic direction of the Luftwaffe at either the strategic or operational level. When Hitler tried to intervene more in the running of the air force later in the war, he was faced with a political conflict of his own making between himself and Göring, which was not fully resolved until the war was almost over. In 1940 and 1941, Göring's refusal to cooperate with the Kriegsmarine denied the entire Wehrmacht military forces of the Reich the chance to strangle British sea communications, which might have had strategic or decisive effect in the war against the British Empire.

Now answer this question: What did the Kriegsmarine try to gain control over?
aircraft