Eagle Squadrons. ES 71 "First From the Eyries", ES 121 "For Liberty", and ES 133 "Let us to the Battle"
From the time the first Eagle Squadron was formed in September 1940 until all three squadrons were disbanded and incorporated into the USAAF in September 1942, they destroyed 73 1/2 German planes while 77 American and 5 British members were killed.
Technically, don't most Brits reckon the BoB was pretty much ended in September though? Even though I have seen references to it as ending in October, I remember in 2000 when they had the 60th anniversary it was held on September 17th (although I'm not sure why that exact date was chosen). Also, according to the USAF museum, Eagle squadron pilots did not fly a combat mission until February 5, 1941.
While some nationalities had their own squadrons (like the 303 "Polish" squadron) during the BoB in the summer of 1940, I am not aware of any specific American squadrons before the Eagles. I believe there were 44 Americans serving in the RAF during the summer of 1940, but they were mixed in with other nationalities in various squadrons.
