On December 6, 1917, Halifax, Nova Scotia, was shattered by the largest man-made explosion in history before the atomic age. In the city’s harbor, the French cargo ship Mont-Blanc—its holds crammed with high explosives—collided with another vessel. Flames quickly consumed the doomed ship. Nearby, railway dispatcher Vince Coleman grasped the danger at once. A passenger train, packed with people, was only minutes from entering the blast zone. Instead of escaping, Coleman rushed back to his telegra