It was the heaviest rock sound ever heard and in that moment Heavy Metal was born, created by a young band from Birmingham, England barely out of their teens.
And now it's come full circle, drawing to an end with the final eight shows ever by Black Sabbath. Ozzy Osbourne, Tony Iommi and Geezer Butler are returning home to close the final chapter in the final volume of the incredible Black Sabbath story.
Sabbath's farewell tour, The End, is currently wowing fans all over Europe. It will culminate in two nights in their home town at the Genting Arena, Birmingham on Thursday, February 2 and Saturday, February 4.
And when the tour concludes, it will truly be The End – of one of the most legendary bands in rock 'n' roll history.
Singer Ozzy is aware of the band's mortality. Following a short period that took away Lemmy, David Bowie, Prince and others, he's aware that all things must end.
"Lemmy, man," he says. "That broke my heart. If someone was to say to me, 'what's your depiction of the heavy metal rock star?', I'd say Lemmy Kilmister."
Ozzy has had more than his fair share of brushes with the Grim Reaper. He's been down – but not out.
"Just ask my family. I've nearly died loads. I've had several stomach pumps, my heart stopped twice when I broke my neck on a quad bike.
"I haven't drunk for three years, I haven't smoked for 12 years, I don't do drugs any time. It's cool."
The band no longer features founding drummer Bill Ward, who left the fold in 2012 after a contract dispute. Ozzy, Tony and Geezer thundered on, releasing 13 in 2013, and embarking on a world tour.
They decided not to do a final album because they didn't want it to fall short of the No1 they achieved with 13.
But despite this being the band's final tour, Ozzy won't be retiring. "I'm not going to stop entirely," he says.
"We're just going to go in different directions.
Black Sabbath has been 'through the mill' he says, 'over the years'.
Ozzy was famously fired in 1979 because his lifestyle was untenable. Iommi said of the time: "We were all doing a lot of drugs, a lot of coke, a lot of everything, and Ozzy was getting drunk so much at the time. We were supposed to be rehearsing and nothing was happening." That prompted Osbourne's solo career and he released seven multiplatinum albums. The band got together for 1985's Live Aid and again in 1992. Eventually, in 1997, the original Sabbath line-up reconvened for the Ozzfest tour. Those shows resulted in the live Reunion album.
Gradually, they started writing and Ozzy was thrilled that 13 proved so popular.
"To come back and be friends with my buddies who I started up with all those years ago," he says, "it's a closure for me to have a chapter of my life which I can say, 'well, we came, we saw, we had a good time, and now it's over'. And so it's like any relationship. I'm glad we ended up having more or less whatever has gone on between us over the years."
Butler adds that the band couldn't carry on for much longer. "So the natural thing to do is to all agree on one last tour. And we all agreed that there won't be any more Sabbath after this. It's like a natural progression kind of thing; a natural end to the band."
By Andy Richardson