On the morning of December 6, 1917, Halifax was a beautiful, peaceful and prosperous city. Within hours it was devastated by the biggest accidental explosion the world had ever seen. The blast was caused by a mid-harbour collision between a French munitions ship carrying almost 3,000 tons of explosives and a Belgian relief vessel. Sixteen hundred people died, and nearly 20% of the city's population--9,000-- were injured. The city's entire north end was flattened by the explosion and the tidal wave that followed. In "Just One Big Mess": The Halifax Explosion, 1917, poignant photos and the voices of survivors help tell the tragic story of an event whose enormity still resonates today.