Leadbelly had already received a pardon from the Governor of Texas several years prior, after writing a song in his own defense, relieving himself of a rather lengthy prison sentence. This time, he found himself locked up in Louisiana. Lucky for him, though, folk song collector, extraordinaire, John Lomax came across him while Leadbelly was on a chain gaing. Leadbelly sang him "Goodnight Irene." Lomax brought the song to the governor, who freed Leadbelly on the condition that he would be under Lomax's care. The musician, of course, went on to become one of the most influential African-American artists in history, all thanks to "Goodnight Irene."
The song, however, was not written by Leadbelly. Its origins actually stretch back to a song by Gussie L. Davis in 1889, and Leadbelly learned the song from his uncle.
After Leadbelly's "discovery" and consequent fame from the song in the 1940s, The Weavers picked it up and hit number one with it in 1950, a year after Leadbelly's death. Since then, it's also been recorded by Ry Cooder, Jerry Lee Lewis, Johnny Cash, The Chieftains, Tom Waits and Peter, Paul and Mary, to name a few.