Obama also compared Mandela to American liberators like civil rights icon Martin Luther King Jr. and President Abraham Lincoln.
"Born during World War I, far from the corridors of power, a boy raised herding cattle and tutored by elders of his Thembu tribe - Madiba would emerge as the last great liberator of the 20th century," he said, according to his prepared remarks. "Like Gandhi, he would lead a resistance movement - a movement that at its start held little prospect of success. Like King, he would give potent voice to the claims of the oppressed, and the moral necessity of racial justice. He would endure a brutal imprisonment that began in the time of Kennedy and Khrushchev, and reached the final days of the Cold War. Emerging from prison, without force of arms, he would - like Lincoln - hold his country together when it threatened to break apart."