Halifax 1917: The Largest Pre-Nuclear Blast

At 8:45 in the morning on the 6th of December, 1917, two ships brushed each other at one knot in the narrow channel of Halifax Harbour. One was the Norwegian steamer SS Imo, riding high and empty, bound for New York to pick up Belgian relief supplies. The other was the French freighter SS Mont-Blanc. Mont-Blanc was loaded, in her holds and lashed to her decks, with 2,300 tons of picric acid, 200 tons of TNT, ten tons of guncotton, and 246 tons of benzol — a high-octane motor fuel — stacked in steel drums on the open foredeck. She was sailing into a city of 50,000 people without a guard ship and without flying any warning flag. Halifax did not know.

The collision itself was almost gentle. Imo's bow opened a wedge in Mont-Blanc's number one hold and then disengaged. As Imo's screw reversed, steel scraped steel, and a single spark caught the benzol vapour pouring from the burst drums. Within seconds the foredeck was a sheet of orange fire. The French crew, who knew exactly what was under their feet, abandoned ship in two lifeboats and rowed for the Dartmouth shore screaming warnings nobody could hear over the noise. Mont-Blanc, burning and unmanned, drifted to Pier 6 in the working-class Richmond District and beached herself against the wooden pilings.

For the next nineteen minutes the city watched. Office workers came to the windows. Schoolchildren pressed against glass. A fire engine, the Patricia, pulled up at the pier with eight men aboard. A whaler from the cruiser HMS Highflyer rowed out to lash a hawser to the burning ship's stern. The first cable was deemed too thin and a ten-inch hawser was being fetched.

At 9:04 and 35 seconds, Mont-Blanc detonated. The blast released the energy of 2.9 kilotons of TNT — the largest accidental human-made explosion in history, a record that stood until the atomic age. Temperatures at the centre touched 5,000 degrees Celsius. White-hot iron rained on the city. Mont-Blanc's anchor shaft, weighing 1,140 pounds, was hurled 2.35 miles inland and is still mounted there today. A pressure wave displaced the harbour itself, throwing a tsunami onto the Dartmouth shore that carried Imo up onto dry land and obliterated the Mi'kmaq village of Turtle Grove at Tufts Cove.

In Richmond, every building inside an 800-metre radius simply ceased to exist. The Acadia Sugar Refinery, a brick fortress, was levelled. Twelve thousand buildings were destroyed or damaged inside a 2.6 kilometre circle. Coal stoves in flattened houses tipped over and set the wreckage burning, trapping survivors in their own basements. Billy Wells, the only one of the eight men on the Patricia to live, was found naked, his clothes torn off by the blast wave, walking among bodies hung in telegraph wires.

The deaths came in three waves. The blast killed roughly 1,600 outright. Three hundred more died later of injuries. The final body, a caretaker buried in the rubble of the Exhibition Grounds, was not recovered until the summer of 1919. The official Remembrance Book lists 1,782 names and is still not considered complete, because the Mi'kmaq dead at Tufts Cove and the Black community of Africville were never fully counted. Nine thousand more were injured. In the days after the explosion, ophthalmologists in Halifax performed 249 enucleations — surgical removal of an eyeball — because so many spectators had been watching the harbour fire when the windows in front of them flew inward as needles of glass. Sixteen of those people lost both eyes.

One man saw the disaster coming and chose to die at his post. Vince Coleman was a railway dispatcher in the Intercolonial Railway yard, 230 metres from Pier 6. A sailor running from Mont-Blanc told him what was in the hold. Coleman and his colleague started to run. Then Coleman remembered the overnight passenger train from Saint John, due at the station within minutes with 300 people aboard. He went back to his telegraph and tapped a final message: "Hold up the train. Ammunition ship afire in harbor making for Pier 6 and will explode. Guess this will be my last message. Good-bye boys." The wire carried his warning along the line. The Saint John train was halted at Rockingham, four miles short. Coleman was killed at his key.

A blizzard buried the city the following day, dumping sixteen inches of snow on the shelterless. Boston sent the first relief train through, and Massachusetts contributed $750,000 — a debt Halifax has repaid for over a century by sending the Boston Common's official Christmas tree every December. Pediatric surgery, modern triage protocols for blast trauma, and the body-identification system later adopted internationally were all forged in the Chebucto Road School morgue in the days that followed. The Canadian National Institute for the Blind became, almost overnight, a world centre.

The judicial inquiry under Justice Arthur Drysdale, in February 1918, blamed Mont-Blanc's captain Aimé Le Médec, her pilot Francis Mackey, and the Royal Canadian Navy's chief examining officer alone. Manslaughter charges were filed against all three, and all three were dismissed within months on insufficient evidence. The civil case dragged through the Supreme Court of Canada and finally to the Judicial Committee of the Privy Council in London, which ruled on 22 March 1920 that Mont-Blanc and Imo were equally to blame. Nobody was ever convicted. When Time magazine reported on Hiroshima twenty-eight years later, it measured Little Boy by saying the bomb was seven times the size of the Halifax Explosion.