One of the greatest maritime disasters in history is reexamined in light of new evidence in this revealing chronicle of the 1917 Halifax explosion.   On December 6, 1917, harbor pilot Francis Mackey was guiding the SS Mont Blanc, a French munitions ship, into Bedford Basin to join a convoy across the Atlantic when it was rammed by the Belgian Relief vessel SS Imo. The resulting massive explosion destroyed Halifax's north end and left at least two thousand people dead, including pilot William Hayes aboard Imo. The tragedy left the country in shock--and looking for someone to blame.   Federal government and naval officials found in Pilot Mackey a convenient target for public anger. Charged with manslaughter, he was imprisoned, villainized in the press, and denied his pilot's license even after the charges were dropped. A century later he is still unfairly linked to the tragedy.   Through interviews with Mackey's relatives, transcripts, letters, and newly exposed government documents, author Janet Maybee explores the circumstances leading up to the Halifax Explosion, the question of culpability, and the unjust, deliberate persecution that followed for Mackey and his family.