Led Zeppelin is best known for its legendary hard-rock anthems, but one of the band's most enduring songs came from a place of profound loss. The band's beloved 1979 ballad "All My Love" was born out of unimaginable tragedy, written after the death of lead singer Robert Plant 's 5-year-old son, Karac Karac, the rocker's second child with former wife Maureen Wilson , died of a stomach infection in 1977 while Plant was on tour in the U.S. with Led Zeppelin.