During World War II, he served with the joint chiefs-of-staff and the State Department. In 1946 he joined the secretariat of the United Nations and served on the UN Palestine Commission in 1947. After Count Bernadotte was assassinated in 1948, he carried on negotiations between the warring Arabs and Jews with such skill that he was able to arrange an armistice between them. For this achievement he was awarded (1950) the Nobel Peace Prize, the first awarded to a Black American.