In February of 1975, Led Zeppelin released their sixth studio album, Physical Graffiti. The double album went platinum 16 times. After the album released, all six of Led Zeppelin's first six albums were on the Billboard charts simultaneously.
It seemed like nothing could slow down the supernova that was Led Zeppelin.
Then, on August 4, 1975, singer Robert Plant was seriously injured in a car crash while vacationing in Greece. Plant's wife at the time, Maureen, was also injured. Their kids walked away from the crash without significant injury.
The second leg of the band's tenth North American tour was cancelled. It would be two years before they would tour again.
Plant's accident was the beginning of the end for Led Zeppelin.
Prior to the accident, Zeppelin released six albums in seven years. They toured constantly.
After the accident, they released two more albums: Presence and In Through the Our Door. They toured North America only one more time. That tour was tragically shortened by the death of Plant's son, Karac.
The difficulties experienced by Plant over the second half of 1970's absolutely sucked the life out of Robert Plant. While it was ultimately the death of drummer John Bonham that ended Led Zeppelin 1980, many believe that Plant was done well before that.