Prof. Donald wrote over thirty books, including well received biographies of Abraham Lincoln, Thomas Wolfe and Charles Sumner. He specialized in the Civil War and Reconstruction periods, and in the history of the South.Donald is best known for his biography of Abraham Lincoln, which was praised by Eric Foner as the best biography of Lincoln, and by Bill Clinton who called it "one of the best biographies on any person in politics," as well as his Pulitzer-Prize winning biographies of politician Charles Sumner and writer Thomas Wolfe.