Jazz standard and Billy Strayhorn's "Take the 'A' Train" (1941). With the big bands struggling to keep going during World War II, a shift was happening in jazz in favor of smaller groups. Some swing era musicians, such as Louis Jordan, later found popularity in a new kind of music, called "rhythm and blues", that would evolve into rock and roll in the 1950s. Bebop emerged in the early 1940s, with Charlie Parker, Dizzy Gillespie and Thelonious Monk leading the way. It appealed to a more specialized audiences than earlier forms of jazz, with sophisticated harmonies, fast tempos and often virtuoso musicianship.
Charlie Parker November 26, 1945, Parker led a record date for the Savoy label, marketed as the "greatest Jazz session ever." Recording as Charlie Parker's Reboppers, Parker enlisted such sidemen as Gillespie and Miles Davis on trumpet, Curly Russell on bass and Max Roach on drums. The tracks recorded during this session include "Ko-Ko", "Billie's Bounce" and "Now's the Time". In 1952 Parker and Gillespie released an album entitled "Bird and Diz". Shortly afterward, the Parker/Gillespie band traveled to an unsuccessful engagement at Billy Berg's club in Los Angeles. Most of the group returned to New York, but Parker remained in California,