Halifax was devastated on 6 December 1917 when two ships collided in the city's harbour, one of them a munitions ship loaded with explosives bound for the battlefields of the First World War. The result was the largest human-made explosion prior to the detonation of the first atomic bombs in 1945. The north end of Halifax was wiped out by the blast and subsequent tsunami. Nearly 2,000 people died, another 9,000 were maimed or blinded, and more than 25,000 were left without adequate shelter.

Wartime Harbour

Halifax was a busy, wartime port city in 1917, its harbour crowded with merchant vessels and warships from Canada and Britain. The city’s population of nearly 50,000 was swollen by the constant coming and going of naval officials, sailors, and troops bound for service in Europe. With one of the finest ice-free harbours in North America, Halifax was an important staging area for trans-Atlantic convoys, which collected in the protected inner expanse of Bedford Basin before ferrying supplies and soldiers to the war effort.

Two of those merchant ships were the Norwegian vessel Imo, en route to New York to pick up relief supplies for the beleaguered population of war-torn Belgium, and the French munitions ship Mont-Blanc — filled with tons of benzol, picric acid, TNT and gun cotton — arriving to join a convoy across the Atlantic.


The Imo was departing the harbour on the morning of 6 December 1917. It was travelling south through the Narrows, the harbour's tightest navigation section, moving faster than it should and passing to the left (port side) of oncoming ships, rather than to the right (starboard), which was customary. The Mont-Blanc was entering the harbour bound for Bedford Basin when it encountered the Imo in the Narrows sailing toward it. Not only did incoming ships (in this case Mont-Blanc) have right-of-way over outgoing vessels, but the Imo was also sailing too far to the left, in what should have been Mont-Blanc's path.

After a series of whistles and miscommunications between the officers and pilots on the two ships, the Imo struck the starboard bow of the Mont-Blanc, generating sparks that ignited benzol stored on Mont-Blanc's deck; the burning liquid then seeped into the holds.

For nearly 20 minutes the Mont-Blanc burned, sending a huge plume of black smoke into the sky, attracting the attention of people on shore, including children on their way to school. The spectacle drew many residents to their windows and others towards the ship itself, including teams of firefighters and sailors from other ships wanting to put out the fire on the Mont-Blanc.

Few understood the danger, except for a handful of harbour and naval officials, and the French-speaking crew and the local harbour pilot of the Mont-Blanc, who fled the ship after the fire broke out, rowing desperately in lifeboats for the Dartmouth side of the harbour. As they did so, the crippled and burning Mont-Blanc drifted towards Pier 6 on the Halifax shore, a busy area containing residential homes, businesses, moored ships and a large sugar refinery.

Vincent Coleman

One man on shore who did know an explosion was imminent was Vincent Coleman, a railway dispatcher who worked in the nearby rail yards. He was warned by a navy man during the fire about the Mont-Blanc'sdeadly cargo.

Coleman controlled the busy freight and passenger rail traffic coming and going from the Halifax peninsula. As the Mont-Blanc burned and the minutes ticked by, Coleman stayed at his post, tapping out a message on his telegraph key, warning officials at stations up the line to stop any trains — including the 8:55 a.m. train from Saint John, New Brunswick, with hundreds of passengers on board — from entering Halifax. It's not clear whether Coleman was actually responsible for holding up the Saint John train, but his message, in the final minutes of his life, was clear:

"Hold up the train. Ammunition ship afire in harbour making for Pier 6 and will explode. Guess this will be my last message. Goodbye boys."

Explosion and Tsunami

The Mont-Blanc exploded just before 9:05 a.m. More than 2.5 km2 of the north end of Halifax, then known as Richmond, was totally levelled, either by the blast, the subsequent tsunami that washed over the neighbourhood, or the raging fire caused when structures collapsed inward on lanterns, stoves and furnaces. Homes, offices, churches, factories, vessels, the railway station and freight yards — and people in the immediate area — were obliterated. Farther from the epicentre, Citadel Hill deflected shock waves away from south and west Halifax, where shattered windows and doors were the predominant damage. Across the harbour, Dartmouth suffered devastation to a lesser degree, since its north section was sparsely developed. However, the Mi’kmaq settlement at Tuft’s Cove was completely destroyed.

The blast shattered windows in Truro, 100 km away, and was heard in in Prince Edward Island. The crew of the fishing boat Wave, working off the coast of Massachusetts, even claimed to have heard the boom rumbling across the ocean.

Author Laura MacDonald describes the ferocity of the explosion in her book, Curse of the Narrows:

"The air blast blew through the narrow streets, toppling buildings and crashing through windows, doors, walls, and chimneys until it slowed to 756 miles an hour, five miles below the speed of sound. The blast crushed internal organs, exploding lungs and eardrums of those standing closest to the ship, most of whom died instantly. It picked up others, only to thrash them against trees, walls, and lampposts with enough force to kill them. Roofs and ceilings collapsed on top of their owners. Floors dropped into the basement and trapped families under timber, beams and furniture. This was particularly dangerous for those close to the harbour because a fireball, which was invisible in the daylight, shot out over a 1–4 mile area surrounding the Mont-Blanc. Richmond houses caught fire like so much kindling. In houses able to withstand the blast, windows stretched inward until the glass shattered around its weakest point, sending out a shower of arrow-shaped slivers that cut their way through curtains, wallpaper and walls. The glass spared no one. Some people were beheaded where they stood; others were saved by a falling bed or bookshelf. . . . Many others who had watched the fire seconds before awoke to find themselves unable to see."

The blast shot vapourized sections of the ship and cargo upwards in a great fireball. The ship's anchor was sent flying across the city and over the Northwest Arm, nearly 4 km away (where it remains to this day). Meanwhile, burning metal fragments of the ship showered down on Halifax, along with a black rain of carbon particles.

People were also blown through the sky. Charles Mayers, third officer of the vessel Middleham Castle, was picked up and dropped nearly 1 km from his ship, landing atop Fort Needham Hill. "I was wet when I came down," Mayers said. "I had no clothes on when I came to, except my boots. There was a little girl near me and I asked her where we were. She was crying and said she did not know where we were. Some men gave me a pair of trousers and a rubber coat."

Death and Destruction

Across Halifax there were miraculous stories of survival. And equally, stories of tragedy. Many children were killed on their walk to school that morning, or blinded by flying glass. Those that survived the blast stumbled home, only to find their houses shattered, or their parents dead or wounded among the wreckage.

Nearly 2,000 people either died instantly, or succumbed to their injuries in the days that followed. Morgue records from 1918 show 1,611 known dead or missing — about a third of them under the age of 15. By 2004, the number of dead had been revised at 1,952. Nine thousand more were wounded, including 300 blinded or partially blinded by flying glass.

More than 1,500 buildings were destroyed and 12,000 damaged. Six thousand people were made homeless among more than 25,000 overall that lacked proper shelter after the explosion — a problem made worse by the winter blizzard that struck Halifax the next day. Total property damage amounted to an estimated $35 million.

Halifax Explosion Map
Plan showing devastated area of Halifax City, N.S.

N.S. Board of Insurance Underwriters Nova Scotia Archives Map Collection: V6/240 - 1917 Halifax loc.


Relief assistance was immediate and extensive. Halifax was well served by the legions of well-disciplined naval and army personnel who happened to be in the city at the time of the disaster, providing aid and a semblance of order. The explosion made headlines around the world. Trains from throughout the Maritimes and from Central Canada and New England soon brought medical aid, doctors, food, clothing, building materials and skilled labourers. The continuing assistance organized in nearby Boston, and provided by the Massachusetts-Halifax Relief Committee, was particularly noteworthy.

Money donated by government, industry and individuals worldwide eventually totalled some $30 million, and was administered from 1918 to 1976 by the Halifax Relief Commission — created by the federal government to oversee claims for loss and damage, rehousing and the rehabilitation of explosion victims.


Halifax's angry survivors demanded answers — and scapegoats — in the wake of the tragedy. At first there were rumours that German saboteurs were behind the explosion. However, a judicial inquiry — heavily influenced by the aggressive tactics of the lawyer hired to represent the owners of the Imo — quickly focused blame on three men: Aimé Le Médec, the Mont-Blanc's captain; Francis Mackey, the harbour pilot on board Mont-Blanc; and Frederick Wyatt, the naval officer in command of the harbour. On 4 February 1918, the inquiry found Mont-Blanc solely at fault for the disaster.

Le Médec, Mackey and Wyatt were arrested and charged with manslaughter, although the charges were later dropped for lack of evidence. In 1919 the inquiry's conclusions were appealed to the Supreme Court of Canada, which declared that both Mont-Blanc and Imo were equally at fault — a verdict upheld by the Privy Council in London, at that time Canada's highest judicial authority. Ultimately, no one was ever successfully prosecuted for failures leading to the explosion.

In 1958, harbour pilot Francis Mackey told CBC Radio: "[Imo] come out on his wrong side. Broke the rules, come on the wrong side of a steamer on the wrong side up above in the Narrows, and then come down on the wrong side again and struck me . . . There was no ship allowed to come out when a ship incoming was bound in. Had the right-of-way myself but she come out."


There are numerous plaques, markers, pieces of embedded explosion wreckage, and gravestones scattered throughout Halifax that commemorate the disaster. One of the most obvious reminders is the city's famous Hydrostone neighbourhood — a series of housing blocks built in the once-devastated north end, using Hydrostone bricks, to provide shelter for homeless victims. The neighbourhood's former name, Richmond, is nowhere to be found.

Next door to the Hydrostone is Fort Needham Park, a grassy hill topped with a concrete memorial where every year on 6 December, people gather above the Narrows to hear the ringing of the memorial's carillon bells, and to remember the victims of the disaster.

Perhaps the most poignant reminder of the tragedy, and the response to it, is the large Christmas tree cut every year from the Nova Scotia woods and erected in central Boston — a gift of thanks from the people of Halifax to a city that provided essential relief and support in the wake of the explosion.