They listened to Obama, a young black U.S. presidential candidate, as he vowed to win the war in Afghanistan.
"We have not the right to lose," Sarkozy echoed him, "We must not allow the Taliban to return."
Obama's visit aroused craze among the European public and the media during his tour and his speech on enhancing transatlantic ties in Berlin has drawn 200,000 people.
The number of audience nearly tripled the most audience he saw at home during his campaign against party rival Hillary Clinton.
His popularity among young people in Europe, analysts say, was partly because of his personal charisma.
Contrary to unilateralism advocated by U.S. President George W. Bush during his first term, Obama also won the hearts of the Europeans by saying that an effective U.S. foreign policy would be based on "our ability not only to project power but also based on the ability to listen and build consensus" with European allies.
His pledge to withdraw U.S. troops from Iraq was to the liking of the French and Germans, who have been opposed to the U.S.-led invasion.
Major media in the three European countries headlined Obama's activities on front pages of newspapers and prime time on TV, creating a sharp contrast to the "deserted" media coverage of McCain's May visit to Europe.
According to a recent Pew global poll, Obama's support in Europe rose to 70-80 percent, similar to that of Bush's presidential rival John Kerry four years ago.
Analysts here believe that Obama's popularity in Europe may not help him laugh to the last in the U.S. presidential election, as after all an American president will be elected by the Americans.