"I didn’t realize then that I would never see Ozzy again after that night," Butler writes of the July 5 "Back to the Beginning" show in England.

Osbourne, who battled Parkinson’s before his death, sat onstage in a black leather chair as he performed for the 42,000-person crowd. He sang five songs by himself, before he was joined by his former bandmates for four Black Sabbath songs.