Masters of The Air–Why are the P-51 Mustangs Escorts flying so close and why so many?

In the Masters of the Air series  episode 7, we see P-51 Mustang escorts for the first time. They are escorting the 100th bomb groups 15 B-17s who are attacking a Ball Bearing plant near Berlin. The video will address the accuracy of the escorts as depicted in the episode. Couple misrepresentation were found and addressed.