Complex sentence: W. E. B. Du Bois was a staunch opponent of nuclear weapons, and in 1950 he became chairman of the newly created Peace Information Center (PIC), which worked to publicize the Stockholm Peace Appeal in the United States.
Split into simpler sentences: W. E. B. Du Bois, a staunch opponent of nuclear weapons, was chairman of the Peace Information Center. It worked to publicize the Stockholm Peace Appeal in the United States.