Though associated with the Swing era, big bands have been a part of every period in jazz. Count Basie's outfit defined Swing in the freewheeling 1940s and the streamlined '50s. Duke Ellington worked in popular music but used his orchestra to explore many artistic directions. Shorty Rogers led a Cool big band, and Dizzy Gillespie led a dynamic Bop orchestra. Gil Evans gained fame by backing Miles Davis, while the Soul Jazz sound of Jimmy Smith hit the charts.