I started with his series on the P47, which has been one of my favourite US fighters since I was a kid. Mainly due to a magazine I got in the 70s called "Wings" that came out every week and was built up to be (pre internet) a multi volume aviation encyclopeadia beyond comparison. There was a big article on "Gabby" Gabreski and his love of the P47 and desire to keep it after most had changed to the P51. I know that Greg in his channel makes quite a point that the hard graft of wearing down the Luftwaffe home daylight defence was mostly done by P38 and P47 pilots in 42 and 43 and early 44.