15 years ago today – on September 12, 2003 – Johnny Cash died in Nashville, Tenn.

“He’s been my inspiration, my faithful friend, my champion- constant oases of unconditional love and support,” Cash’s Highwaymen bandmate Kris Kristofferson told Relix after his passing. “His fierce independence and free spirit, balanced with his love of family, children and his fellow man, will stand as a shining example of the best of what it means to be human. And, he was damned funny, even in the darkest times.”

Through his 71 years, Cash recorded more than 1,500 songs, won 11 Grammy awards and collaborated with the likes of Willie Nelson, Waylon Jennings, Rick Rubin and, of course, his beloved wife and duet partner June Carter.

Despite his countless awards and monetary successes, Cash’s outlaw persona is just as crucial to his musical legacy. He was “The Man in Black,” a figure who spoke to criminals and outcasts more than the glitter-clad country singers of his heyday. His famed performances at Folsom Prison, San Quentin and Österåker Prison are still considered time capsules, capturing not only Cash, but the downtrodden who loved his music so.

Recorded on on February 24, 1969, watch Cash perform “Boy Named Sue” live from San Quentin Prison below: