During WWI, the deep natural harbour of Halifax, Canada was the most important seaport in North America. All neutral merchant traffic, military convoys, and army recruits coming and going from the eastern seaboard came through Halifax first, including shipments of munitions intended for the European front. December 6, 1917, 9:05:35 A.M., the realities of war would have tragic consequences for the people of Halifax and Dartmouth with the biggest accidental explosion the world has ever known.