Keep in mind… during the early bombing runs; bombers were spread out. Once they reached their targets, the Luftwaffe would meet up with them and attack them from all directions thus causing the bombers to take evasive actions and not complete their bomb runs. Some return loaded or were shot down. When LeMay (or Eaker I forget which) took command, he saw the flaw. He ordered his bombers to close up tight, fly straight - yes thru flak and Luftwaffe fighters and DO NOT take evasive action. Drop their bombs and return home….. all WITHOUT a fighter escort. Yes, there were losses.
Later on, Bomber crews demanded fighter escorts on their bomb runs into Germany and they got it. They started using P-47 Thunderbolts. The trouble with P-47 is range. They can go as far as the German border then turn back before losing fuel.
Eventually, a brand new fighter was introduced, the P-51 Mustang which has much better range and faster than the Thunderbolts and escort the bombers deep into Germany AND engage the Luftwaffe fighters.
So my point is the statement claiming the crews of the B-24 Liberators were the "true Masters of the Air" is irrelevant. Again, read the book Masters of the Air. It gives a deeper historical element of the Bomber war.