Sam Parkins, wily explorer of the reeds, is also a phenomenal writer. Here’s a snippet from his memoirs about Louis’s approach to the harmonic “modernism” that so shaped the jazz of the times:
I heard Louis Armstrong the music critic at that dance in Lexington KY, spring 1945. A very clear statement about his loathing for modern music, coming at him like a tornado. Music lesson: For preceding centuries, a song or a complete chorus ended on what’s called the “tonic” – the home key, and the chord that preceded it was called the “dominant”, 4 notes below. Here comes modern, and by 1944 the “dominant” was often replaced by a somewhat purple 7th chord a half-step above the “tonic”. Let’s put our mythical tune in the key of F major; at least 20% of the standard repertoire is in F. Eddie Condon called F “the key of love”. Means the traditional “dominant” chord is C, usually with a 7th. So I’m grooving away with Louis blowing his heart out over the band, and come to an ending, where his up-to-date arranger has modernized things with a G-flat 7th before the “tonic” F. Louis slashes an angry C triad right across it, making him play at least two “wrong” notes, and Louis was incapable of playing wrong notes. “That for your godamned modernism!”.
JAZZ LIVES 
A great story! I did some listening and Sam might have heard “I’ve Got a Gal in Kalamazoo.” Armstrong performed it on an AFRS “Jubilee” Program in 1943, included on an old Moon disc, “Radio Days.”
The song is in Ab and sure enough, instead of a simple ii-V-I progression as Sam mentioned, which would have been Bbm-Eb7-Ab, the tune ends by descending from Bbm to an A7 to an Ab. Armstrong handles it well but I could see him getting annoyed by this at other performances and blowing the changes he heard in his head. Again, a great story!
Pingback: Toke Signals with Steve Elliott | Cannabis Quote Of The Day: Louis Armstrong