The Halifax Explosion, Dec 6, 1917 Canada sent convoys to Europe On this day, a ship(Mont Blanc) with ammo was rammed by the Norwegian SS Imo in "The Narrows" section of the Halifax Harbour. and blew up Largest explosion in the world up until the atomic bombs in WWII About 20,000 people were killed by the debris, fires or collasped building, and an estimated 9,000 were injured. The Halifax Explosion remains to be the worlds largest man made accidental explosion.