When David Herbert Donald delivered his final lecture at Harvard in 1992, some of his teaching assistants wept. Mandarins from the History Department joined hundreds of students for the concluding performance, a brilliant, somewhat discursive talk on the meaning of the Civil War. “Lecture” isn’t quite right: Donald charms his audience with rich historical vignettes and engages them in big-issue dialogues. His conversation is cool as a mint julep under a magnolia tree in Nashville, but the Mississippi native is more than a lesser-known Shelby Foote. Donald has shaped Civil War and Lincoln studies more than any other living historian, winning two Pulitzers in the process. His recent biography of Lincoln, the first full-length scholarly work on the 14th president in a generation, has already become required reading for students of the war. Donald will discuss Lincoln at 12:30 p.m. at the National Archives Theater, 7th & Pennsylvania Ave. NW. FREE. (202) 501-5000; at 7 p.m. at Politics & Prose, 5015 Connecticut Ave. NW. FREE. (202) 364-1919. (John Cloud)