The Halifax explosion took place on December 6 , 1917 when a French cargo ship with explosives collided with a Norwegian ship in the harbor in Halifax , Nova Scotia , Canada . The Halifax Explosion occurred on Thursday , December 6 , 1917 , when the city of Halifax , Nova Scotia , Canada , was devastated by the huge detonation of the SS Mont-Blanc , a French cargo ship , fully loaded with wartime explosives , which accidentally collided with the Norwegian SS Imo in `` The Narrows '' section of the Halifax Harbour .