Who is Secretary of State William Seward from The Fiery Trial: Abraham Lincoln and American Slavery and what is their importance?

Secretary of State, William H. Seward, serves as one of Lincoln's closest advisors during his years in the White House. When Lincoln signed the Emancipation Proclamation, Seward advised him not to go public...... fearing the timing and what its impact would do to the country while it was in the midst of a Civil War. Seward later became a target of the same assassination plot that ended Lincoln's life.