What was the Halifax Explosion?

The Halifax Explosion was a massive explosion in Halifax Harbour on December 6, 1917 when the French munitions ship SS Mont-Blanc collided with the Norwegian ship SS Imo and detonated about 2,653 tonnes of high explosives. About 1,950 people were killed, 9,000 injured, and the Richmond district of Halifax was destroyed in what was the largest man-made explosion in history before the atomic bomb of 1945. The explosion produced a 5-metre tsunami and a shockwave felt as far away as Cape Breton Island.

Halifax was a major North Atlantic convoy port during the First World War. The harbour was busy with merchant shipping and naval traffic. The Mont-Blanc was a 3,121-ton French steamship that had loaded a cargo of TNT, picric acid, guncotton, and benzol fuel at New York and was joining a convoy bound for the European war zone. The Imo was a Norwegian relief ship under charter to the Belgian Relief Commission. The two ships collided in the Narrows of Halifax Harbour at about 8:45 AM on December 6, 1917 due to navigational errors and pilots' miscommunication. The Mont-Blanc caught fire after the collision; her crew abandoned ship and rowed to the Dartmouth shore.

The Mont-Blanc drifted toward the Halifax shore as crowds of dock workers, ship's crews, and school children watched the spectacular fire. At 9:04:35 AM the cargo detonated. The explosion produced a fireball reaching about 1,800 metres high, generated temperatures of about 5,000 degrees Celsius, and threw fragments of the Mont-Blanc up to 5 kilometres. The shockwave destroyed buildings in a 2-kilometre radius. The Richmond district of Halifax was almost completely destroyed; nearby Mi'kmaw communities at Tufts Cove and Africville also suffered devastation. The Imo was driven ashore on the Dartmouth side. The resulting tsunami destroyed structures along the harbour shore.

The casualty toll was catastrophic. About 1,950 people were killed, 9,000 injured, and 25,000 left homeless. The Mi'kmaq community at Turtle Grove (Tufts Cove) was completely destroyed. The explosion was followed by a major blizzard that began that evening. International relief poured in. Massachusetts sent the Massachusetts Relief Train arriving December 8, 1917, including doctors, nurses, and supplies. In gratitude, Halifax has annually since 1971 sent a Christmas tree to Boston, where it is displayed at Boston Common as a reminder of the Massachusetts response. The Halifax Relief Commission, established by the Maritime Province governments and federal government, coordinated rebuilding through the 1920s. The Halifax Explosion is commemorated by the Halifax Explosion Memorial Bell Tower in Fort Needham Memorial Park (1985) and the Maritime Museum of the Atlantic exhibit. The wreck of the SS Mont-Blanc's anchor is at the Halifax Citadel.