June 3

Battle of Cold Harbor — Grant's Bloodiest Hour

Union General Grant ordered a frontal assault on heavily fortified Confederate positions at Cold Harbor. In under an hour, the Union Army suffered 7,000 casualties — men who had written their names on paper and pinned them to their backs before the assault, knowing they would die.

Cold Harbor was Grant's greatest tactical blunder and so disturbed him that he later wrote it was the only battle he wished he had not fought; but Grant continued the campaign.