Country-rock pioneer John Dawson, a co-founder of the New Riders of the Purple Sage, died Tuesday (July 21) following a lengthy battle with stomach cancer. Nicknamed "Marmaduke," he and the Grateful Dead's Jerry Garcia formed the band in 1969 in the San Francisco area as an outlet for Dawson's songwriting and Garcia's desire to play pedal steel guitar. Dawson's songwriting credits include the New Riders' "Glendale Train" and "Last Lonely Eagle." He also served as a guest musician on the Grateful Dead's country-leaning Workingman's Dead and American Beauty albums and co-wrote one of the Dead's most famous songs, "Friend of the Devil." The New Riders of the Purple Sage released eight albums on Columbia Records during the '70s. In 1997, Dawson retired to Mexico and became an English teacher. He reunited with members of the New Riders in 2007 during the 40th anniversary Summer of Love concert in San Francisco's Golden Gate Park.