When Nelson Mandela was alive he participated in many acts of peacemaking. He was highly active in the anti-apartheid movement when he was younger. Mandela was arrested for (so called) life, even though he was only in for 27 years. He won the Nobel Peace Prize in 1993 and became the first black South African president. He died of Lung infection in 2013.
Martin Luther King Junior was very influenced by Gandhi. He used the some of the same tactics as Gandhi too. MLK didn't mind jail time either, like Gandhi didn't because it helped with the cause. He was shot and died in 1968. Without Gandhi, MLK's efforts might not have gone as well as they did when he was influenced by Gandhi.
Mahatma Gandhi wasn't called the great-souled one for no reason. He wanted to free India from the British rule. Gandhi believed that his protests should be peaceful. He was the first person who used civil disobedience as a peaceful protest tactic. Gandhi was shot to death in 1948. Without this great historic figure India might still be a British Colony.