Who is Harry Truman from Eleanor Roosevelt: A Life of Discovery and what is their importance?

Harry Truman was serving as FDR's Vice President when he died during his fourth term. As a result of FDR's death, Truman was sworn in as President, and one of his first official acts was to nam FDR's widoe, Eleanor, among the first group of delegates to the newly formed United Nations. President Truman referred to Eleanor as the "First Lady of the World".