<P> In England, electric blues took root there during a much acclaimed Muddy Waters tour . Waters, unsuspecting of his audience's tendency towards skiffle, an acoustic, softer brand of blues, turned up his amp and started to play his Chicago brand of electric blues . Although the audience was largely jolted by the performance, the performance influenced local musicians such as Alexis Korner and Cyril Davies to emulate this louder style, inspiring the British invasion of the Rolling Stones and the Yardbirds . </P> <P> In the late 1950s, a new blues style emerged on Chicago's West Side pioneered by Magic Sam, Buddy Guy and Otis Rush on Cobra Records . The "West Side sound" had strong rhythmic support from a rhythm guitar, bass guitar and drums and as perfected by Guy, Freddie King, Magic Slim and Luther Allison was dominated by amplified electric lead guitar . Expressive guitar solos were a key feature of this music . </P> <P> Other blues artists, such as John Lee Hooker had influences not directly related to the Chicago style . John Lee Hooker's blues is more "personal", based on Hooker's deep rough voice accompanied by a single electric guitar . Though not directly influenced by boogie woogie, his "groovy" style is sometimes called "guitar boogie". His first hit, "Boogie Chillen", reached number 1 on the R&B charts in 1949 . </P> <P> By the late 1950s, the swamp blues genre developed near Baton Rouge, with performers such as Lightnin' Slim, Slim Harpo, Sam Myers and Jerry McCain around the producer J.D. "Jay" Miller and the Excello label . Strongly influenced by Jimmy Reed, Swamp blues has a slower pace and a simpler use of the harmonica than the Chicago blues style performers such as Little Walter or Muddy Waters . Songs from this genre include "Scratch my Back", "She's Tough" and "I'm a King Bee". Alan Lomax's recordings of Mississippi Fred McDowell would eventually bring him wider attention on both the blues and folk circuit, with McDowell's droning style influencing North Mississippi hill country blues musicians . </P>

The early blues musicians used which combination of instruments