There has never been a bloodier day in American history than Sept. 11, 2001. No other single atrocity or catastrophe even comes close. The terrible toll at the World Trade Center — 6,986 believed perished so far — dwarfs anything in the experience of Americans. The previous grim standard was set Sept. 17, 1862, at the Civil War battle along Antietam Creek, on the outskirts of Sharpsburg, Md., where Union and Confederate soldiers fought from sunrise to sundown and left 3,654 comrades on the field. The next bloodiest single day came June 6, 1944 — code-named D-Day — when ...