London ? Twenty years after a scruffy one-hit wonder first demonstrated his gift for lofty dreams and grandiose statements, hundreds of the world’s top performers and more than 1 million fans united for 10 free concerts across the globe aimed at fighting African poverty.

But the ultimate success of the Live 8 extravaganza will be judged by whether the world’s most powerful leaders, gathering next week for the Group of Eight summit meeting, listen to Geldof’s demands for debt forgiveness, trade concessions and $25 billion in aid for Africa.

“History and the generations to come will judge our leaders by the decisions they make in the coming weeks,” former South African president Nelson Mandela said after taking the stage in Johannesburg, where the crowd of more than 8,000 people gave him a five-minute ovation. “I say to all those leaders: Do not look the other way, do not hesitate. : It is within your power to prevent a genocide.”

In Philadelphia, on the Independence Day weekend, actor Will Smith called the festivities a worldwide “declaration of interdependence.”

“Today we hold this truth to be self-evident: We are all in this together,” Smith said. Beamed around the world by satellite, he led the audience in snapping their fingers every three seconds, signifying the child death rate in Africa.

Geldof’s claim that 3 billion people around the world were watching Saturday seemed overblown, as did talk in Philadelphia that a million people were on hand. But Live 8 was huge nonetheless, with a mile-long crowd stretching from the front steps of the Philadelphia Museum of Art and America Online saying that more than 5 million people sampled its live video streams, which broadcast all 10 concerts in their entirety.

The first concert kicked off in Japan, then rolled on to events in Moscow, Johannesburg, Edinburgh, Scotland, London, Paris, Berlin, Barrie, Ontario and Philadelphia.