On 6 December 1917, the French freighter SS Mont Blanc sailed into Halifax harbour. The ship, laden with munitions, was en route from New York to Le Havre, France, and Halifax was its last port of call before it began its Atlantic run. The Mont Blanc was carrying 2,300 tons of picric acid (used in the manufacture of artillery shells), 200 tons of explosives, and 10 tons of gun cotton. Several barrels of Bezol, a high-octane fuel, were stacked on deck.
As the Mont Blanc entered the harbour, it collided with the Norwegian ship Imo , a vessel bound for Belgium. Some of the barrels broke loose. The highly flammable Bezol spilled out and caught fire almost immediately. The French crew was unable to contain the fire, and Captain Medec ordered them to abandon ship. The Mont Blanc drifted farther into the harbour, and the flaming vessel came to rest along Pier 6. The British cruiser HMS Highflyer was moored nearby.
At 9:05, the Mont Blanc exploded with a thunderous roar. The force of the blast threw several British sailors into the superstructure of the HMS Highflyer , killing them instantly. The explosion levelled two square kilometres of Halifax, and numerous fires broke out. Fragments of the Mont Blanc rained down on the harbour and city, some landing as far as five kilometres away. The blast also created a huge wave that crashed into the shore, sinking several small vessels and devastating the buildings that lined the harbour. The explosion claimed the lives of 1,630 people, and the damage to houses and property was staggering.