What did w. e.b. dubois have in common with harriet martineau?

Both Harriet Martineau and W. E. B. Du Bois are both socialists but the former is British and the later is an American. They both were interested by the promise made by the American constitution in the grounds of democracy but were later appalled as the promise was not exactly fulfilled..

Delaware, pennsylvania, new jersey, georgia, connecticut, massachusetts bay, maryland, south carolina, new hampshire, virginia, new york, north carolina, and rhode island and providence plantations where the 13 original colonies