This article was first published in the Christmas 2017 issue of BBC History Magazine


For the people of Halifax on Canada’s eastern seaboard, it was the moment when time stood still – quite literally. At 9.04am on 6 December 1917, hundreds of clocks in the environs of the bustling port came to a sudden halt, capturing the moment that the city was almost blown out of existence. Less than 20 minutes earlier, in the heart of Halifax’s harbour, two huge ships had collided, triggering a chain of events that would lead to the death of hundreds – victims of what was then the largest manmade explosion in history. At the height of the First World War, Canadians had grown used to mass death – almost 40,000 of their compatriots had already lost their lives on the western front – but no one was prepared for this.

The darkest day in Halifax’s history had begun like any other. The port was, as ever, bristling with ships congregating in the shelter of its deep, ice-free harbour. Many of them would have been preparing to make the journey, in convoys, across the Atlantic to a Britain increasingly desperate for foodstuffs grown in Canada’s vast farmlands, as U-boat attacks on Allied shipping increasingly took their toll. Since the outbreak of war, the port had swollen to 50,000 people, many of them soldiers and sailors. Almost 2,000 commercial vessels passed through Bedford Basin (at the north-western end of the harbour) in 1917 alone.

One of those ships was the Norwegian steamer Imo, which, on the morning of 6 December, was heading out of Halifax for New York, to pick up relief supplies intended for the beleaguered people of Belgium.

Meanwhile, outside of the submarine net that protected the port, the French single-screw steamer Mont-Blanc was set to enter the protective confines of the harbour and join a convoy. Its crew was nervous, and with good reason – the Mont-Blanc’s cargoes were filled with crates, kegs and barrels containing no less than 2,925 tonnes of benzol, picric acid, gun cotton and TNT. In peacetime, port authorities would have seen to it that a vessel carrying this explosive cocktail of chemicals was escorted into harbour. But the war had led to such increased shipping that they cut corners in the name of expediency. Mont-Blanc was a massive moving bomb in waiting.

Hasty exit

Imo’s captain and crew were eager to depart Halifax, and when they started steaming south from Bedford Basin, they did so rapidly – partly because the 430ft-long liner was carrying no cargo. Such was Imo’s impatience to be out on the open seas that it passed a number of ships on the left (port side) rather than the customary right (starboard). It did not even reduce speed as it travelled through the Narrows, the harbour’s most constricted area, and where an early morning haze demanded extra caution. Before long, naval traffic had driven the Imo out of its own lane and into one occupied by the approaching Mont-Blanc, a 3,121-ton vessel with a hull 320ft-long and almost 45ft-wide.

Both ships were piloted by experienced Canadian seamen – Francis Mackey on Mont-Blanc had almost 25 years of experience on the water. But a series of whistle warnings from both vessels were misunderstood, and Imo continued along its route, even when Mont-Blanc, which had the right of way, cut its engines.

By then it was too late. From several hundred metres out, both pilots realised that the vessels were on a collision course – one that no amount of frantic turning could avert.

And so, at 8:45am the Imo struck the starboard bow of Mont-Blanc, with a scream and shudder of metal on metal, penetrating nine feet. No one on board the ships was seriously hurt but sparks immediately ignited the benzol aboard the French vessel, which spread burning liquid. As Imo reversed to release the ships, the fire burned rapidly on Mont-Blanc, fed by other chemicals.

The fire onboard Mont-Blanc raged higher with each minute, sending up huge bursts of flame 35 metres high. The spectacle of the fire drew onlookers, many of whom lined the shore, while others moved to the windows of houses, not wishing to brave the cold morning air. The dying ship, now abandoned by its crew, drifted to Pier 6, along the Halifax shore.

An enormous cloud of black smoke drifted over the city, laying thick over the dense houses, businesses and docked vessels near or on the water in the northern part of Halifax, known as Richmond. Those on shore became uneasy, as a series of explosions rocked the ship, with barrels and crates shooting off like rockets. Firefighters moved cautiously towards the unnatural fire, while Royal Canadian Navy sailors braved the heat to close in on the ship, to no avail.

Thrown through walls

One of the many eyewitnesses was Vincent Coleman, a railway dispatcher. He was sat in his office when a navy man burst in and warned him to get away. Coleman, who was aware of Mont-Blanc’s deadly cargo, could have taken the sailor’s advice. But he was responsible for controlling the rail traffic, and he knew a passenger train from Saint John, New Brunswick, with hundreds aboard, was due to arrive at any minute. He raced back to his office and tapped out an emergency telegraph warning to all stations within the vicinity. The train stopped in time. Coleman’s last ever message was: “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.”

When the 2,925 tonnes of explosives aboard the Mont-Blanc detonated, the results were catastrophic. The shockwaves blew outward and upward, generating a massive, 5,000°C fireball that incinerated spectators along the shore and sailors on close-by ships.

Such was the strength of the explosion, it blew the vessel more than 1,000 feet into the air. Much of the ship came apart in the eruption, hurling shards of metal across the city. Its anchor, weighing half a tonne, was later found 2 miles away, where it remains to this day.

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The sonic boom of the explosion was followed by a torrent of air that rushed through Richmond’s streets, smashing houses, factories and even stone buildings. Men, women, children, horses and household pets were lifted and thrown by the force, some projected through buildings and walls. Bodies hung from trees and buildings, some with missing heads and limbs that had been amputated by the force of the blast or the whirling steel. Others died with barely a scratch on them, their lungs collapsed.

The survivors within the epicentre (which extended over several kilometres) were almost all knocked unconscious. They awoke with burst eardrums and blood running from noses. Almost all had shards of glass embedded in their bodies, some as long as kitchen knives. Several hundred awoke forever blinded, including many who had watched the burning Mont-Blanc from behind windows in their homes and businesses.

A void and a tsunami

The 22-year-old sailor Charles Mayers was tossed from the blast more than a kilometre from his ship. He awoke with only his boots on. Next to him was a sobbing little girl who had been blown from another part of the city.

The heat from the explosion was so intense that a 20ft radius of water around the ship instantly evaporated. The void led to a tsunami. Piers and ships were smashed by the wall of water, while unconscious civilians along the shoreline were swept away, many dragged out to sea.

Every single building in Richmond was damaged, most of them reduced to tinder. Stoves that were stoked hot to keep houses warm now spread hundreds of fires, adding to the apocalyptic landscape.

Survivors in the blast zone stumbled to their feet, seconds, minutes or hours later. Concussed and bleeding, they were covered in a sooty, oily grime from the burning chemicals, so that they all looked like they had been dipped in tar. Those who could, stumbled off to look for their families, snaking through the labyrinth of destruction. One eyewitness recounted that they were a “cold, barefooted and torn people”.

All throughout Richmond, small groups of survivors dug frantically through the wreckage to reach their loved ones, ignoring lacerated hands and ripped nails, driven by desperation and fear. Some were found alive; others were already dead. With the widespread devastation, it looked like the war on the western front had come to Canada.

Weaponised debris

Within a few hours, nearby hospitals were overrun and overwhelmed. Even experienced medical professionals recoiled at the wounds. Muscle had been sheared from bone by shards of steel or weaponised debris; eyes were pulped and filled with shards of glass. Some of the injured had cuts so severe and deep that it looked like someone had taken an axe to their bodies, again and again. One lady was brought to the hospital with her face sheared off, exposing her brain. She had been found holding her dead baby, rocking slowly. She died as doctors and nurses raced to care for those who could be saved.

Terrified and distressed children required different care. There were so many young people who had been separated from their parents that nurses could not comfort them all. Bertha Archibald was a pharmacist in one of the hospitals and was dismayed at the mass of broken bodies. She found it hardest to see the little children, their clothes tattered, eyes wide with fright, many standing with arms wrapped around their chests, alone. She found two sooty and bloodied children wailing for their mothers. She placed them gently in a bed. “The little fellows put their arms around each other and their sobs grew less and less as they comforted each other.”

Despite the shock of the blast, Halifax’s authorities rushed to action, organising committees to procure food, clothing and medical supplies for the many makeshift aid centres that were filling up with refugees. The wounded were top priority but the dead also needed to be gathered. The Halifax authorities had experience with mass death after the 1912 Titanic sinking, when the city received 209 bodies. Now, in this new, far more deadly catastrophe, they established a morgue in the Chebucto Road School. Here corpses were stacked like cordwood, several bodies deep, one atop another, stiff as stone. Later, when more space was found, they were laid out, their personal belongings next to them in draw-string bags so that they might be identified by grieving loved ones, who walked between the bodies, hoping not to find a son, father, daughter, sister, brother or mother under the white cloths.

Late in the day, a winter storm blew in. The temperature plummeted overnight and a thick snow fell, reaching 40cm. Most of the raging fires had burned out by then, but hot embers and coals buried under the rubble sizzled during the next day as the snow built up. Dr WB Moore was one who moved through the city looking for survivors. He was shocked by the “weird and desolate spectacle”.

The snow impeded the recovery of those still buried in the debris, and we can never know how many died in the blast, the fires, or from the cold while in their vulnerable state. Many of the dead lay entombed within the ruins, some not found for weeks or months. Others, either vapourised in the initial fireball or dragged out into the harbour by the tsunami, were lost forever.

Morgue records eventually revealed that 1,611 were counted as dead or missing, about a third of whom were under the age of 15. Now, with archivists having combed through the records and census reports – and factoring in those who died of their injuries – the number of dead has been revised to 1,952. At least 9,000 were wounded, and that grim figure includes 300 blinded by shards of glass and other projectiles. During the frantic days after the explosion, one eye specialist removed at least 75 eyeballs, sometimes working on a wife, then her husband, then their children.

Unimaginable loss

“I am alive but do not know why,” wrote Lambert Griffith, a Royal Canadian Navy sailor to his wife. In the months after the explosion, the search for why dominated Halifax. Traumatised survivors demanded an inquiry into who was responsible. There was a series of adversarial trials and the lawyer representing the owners of Imo cast blame on Mont-Blanc’s captain, Aimé Le Médec, and Frederick Mackey, the harbour pilot on board. In a finding of tremendous injustice, Médec and Wyatt were scapegoated in February 1918. The manslaughter charges were later dropped and future appeals and investigations assigned more of the blame on Imo’s captain and crew. Eventually all charges were dropped. No one was held accountable for the tragedy.

In the immediate aftermath of the disaster, aid poured in to Halifax from across America and Canada, money that was used over almost 60 years to care for the injured. But, such were the exigencies of the war that it wasn’t long before the disaster was being overshadowed by events on the western front. Remarkably, the crucial convoys began running again from the port within a few days.

There could be no interference with the war effort. In most parts of the country, people rapidly pushed the losses at Halifax aside. As Canadians continued to fight and die in the trenches, they viewed the events of 6 December 1917 merely as one more disaster in a war that brought unimaginable loss.


Tim Cook is a historian in Ottawa, and author of 10 books including Vimy: The Battle and the Legend (Penguin, 2017). He is a frequent commentator in the media and a member of the Order of Canada.