They say he was slow-yet McClellan assumed command and in two weeks combined two different forces into one, marched on Lee, and defeated him at Antietam. They say he was not a fighter. Antietam is the bloodiest day in American History. History has not treated General George McClellan kindly, but there is another side to the story-the soldiers' side. No US general of the Civil War was adored more by his troops than McClellan, and with good reason...