Mid-way into the swing era, around the late 1930s and 1940s, a handful of young musicians found jobs in big bands. Lester Young played tenor sax with the Count Basle band, Charlie Christian played guitar with Benny Goodman, Charlie Parker, Dizzy Gillespie and Billy Eckstine were with Earl "Fatha" Hines, and Fats Navarro was one of the "Twelve Clouds Of Joy" with Andy Kirk.
What they all had in common was that big band swing music was not to their liking. They wanted to play music they originated, and did not want to be confined to the notes on the manuscript.
Frequently, they would drop in at an all-night club and participate in a jam session, playing for hours at a time. Eventually, such clubs became musicians' hand-out-places where soloist could experiment and develop their improvisations.
Minton's Playhouse in New York City was probably the first club to feature the jam session scene. The house band consisted of Kenny Clarke, (drums), Thelonious Monk, (piano), Nick Fenton, (bass), and Joe Guy, (trumpet).
It was not unusual on any given night to have musicians like Dizzy Gillespie, Charlie Parker, Bud Powell, Ben Webster, Don Byas, Charlie Christian, Jimmy Blanton, Denzil Best and Sid Catlett come in, take out their instruments and join the house band on stage.
This jam session was different from the usual sessions, in which the house band would start out playing a popular tune like "Tea For Two," and the regular swing musicians would play a couple of choruses based on the chord progressions and to improvise around the melody.
The Minton Playhouse jam session would actually challenge the musicians' imagination by playing unusual chord changes without a definite key center, with the drummer providing irregular rhythmic patterns. Often, more than one soloist would improvise and not be aware of what the other musicians were playing. it became a musical free-for-all.
In the early 1940s, this new music was a further development of jazz, and was usually played by small groups. A typical bop group would consist of a saxophone, trumpet, and a rhythm section of piano, bass and drums.
Bop was not the creation of any one individual. There were many musicians who spearheaded this revolutionary development. About 1945, when the swing era came to an end, a group of black jazz musicians developed the "bop" sound by the alteration of the basic chords. With the changing of the melody and the inclusion of complex rhythmic patterns, bop became an expression of revolt.
It was a revolt against the commercial music dominated by white bands. Ross Russell, in his "Be-bop Instrumentation" record changer, summed it up best when he said, "Bebop is the music of revolt. Revolt against big bands, arrangers, vertical harmonies, soggy rhythms, non-playing orchestra leaders, and Tin Pan Alley-against commercial music in general."