You may remember in the torrent of news last year about an event in the port of Beirut, Lebanon. In August of 2020, a warehouse storing 2,750 tons of ammonium nitrate caught fire, causing an explosion strong enough to register on seismographs and was heard as far away as Cyprus, more than 150 miles (240km) away. The details of the accident are still being investigated, but what we do know is that the explosion was equivalent to about 1.1 kilotons of TNT, and it caused at least 207 deaths and 7,500 injuries. It was, undoubtedly, one of the worst man-made disasters in recent memory.
But what if we told you that the Beirut blast, despite the damage it inflicted, wasn’t even the worst accident of its kind – indeed, that there was a disaster like the Beirut explosion, but whose damage and death toll were orders of magnitude worse? Well, there is, and we have the breakdown of that accident for you here today; this is the story of the Halifax Explosion.
The Great War
The year was 1917, and World War 1 was in the middle of its third year. Though the spotlight of the Great War tends to be stolen by the trench warfare of the Western Front, it was the situation on the high seas that proved just as important to the outcome. During the war, Britain and France bought huge amounts of supplies from the United States, from weapons to foodstuffs and beyond, which were then shipped across the Atlantic to the allied countries.
These readily available imports were not an option to the Central Powers, namely the German Empire. At the start of the war, the United Kingdom had its Royal Navy impose a total blockade of German shipping, one that was, even at the time, considered exceptional in its severity; even food was considered “contraband of war”. Although Germany was able to produce sufficient amounts of food in peacetime, the demands of war resulted in many farmers being drafted, along with their draft animals and fertilizer being requisitioned for the war effort. What this meant was that where the Western allies had basically all the food they could eat, Germany was forced to ration.
The Germans were not blind to their dire situation on the ocean, which wasn’t made easier by the fact that it was basically a free-for-all in terms of international law. We’d go into more specifics, but honestly the back-and-forth between Britain and Germany over the rules on submarine warfare and on arming “neutral” merchant ships is a video all on its own. All you need to know is that both countries complained that the other was violating international law, and they were both right. There were no “good guys” in World War 1, really.
This is the background for our scene, which now turns to the Canadian port town of Halifax, Nova Scotia, an important pit stop in the trans-Atlantic convoy system. Halifax at this time had struggled to make a name for itself, but prior to the outbreak of war, the Canadian government had made a huge effort to develop the town as a harbor city. As Canada was still a part of the British Empire at this time, the war resulted in the British authorities adopting Halifax as their base in North America, and the town became the launch pad for supplies being shipped to the front lines. Many ships would load up on supplies from ports in the eastern US, and then stop in Halifax to depart under the protection of British warships. In addition, all neutral ships bound for North American ports had to report to Halifax for inspection, to ensure that they were complying with the British blockade. Finally, to get the point across, a heavy military garrison was installed in the city, including anti-submarine nets in the harbor which were raised at night to prevent any attacks.
All of this sudden attention Halifax was getting resulted in something of a boom. From the start of the war to 1917, a whopping 60,000 people moved to the city, and the weight of goods shipped through the harbor increased by nine times what it was pre-war. And it was on the morning of December 6th, 1917, that a very consequential cargo would enter the harbor.
Failure to Yield
There are two primary actors in this story. The first is the SS Imo, a Norwegian vessel intended to carry relief supplies to Belgium, at the time still under German occupation. The Imo had sailed from the Netherlands and arrived in Halifax on December 3rd for inspection and refueling, intending to continue on to New York afterwards. The captain, Haakon From, had been given clearance to leave Halifax on December 5th, but the coal for his ship had been delayed. By the time refueling was done, the anti-submarine nets had been raised in the harbor, forcing him to wait until morning to depart for New York.
It was while Captain From was sitting in port that our second character sailed onto the scene. The SS Mont-Blanc was a French cargo ship which arrived at Halifax harbor from New York on December 5th, under the command of Aimé Le Medec. In the exact opposite problem of the Imo, the Mont-Blanc arrived at Halifax harbor too late before the submarine nets were raised, forcing it to wait outside the port until morning when the nets would be lowered. Its cargo was a full load of TNT, picric acid, guncotton, and benzol fuel – highly flammable, and highly explosive. Normally, ships carrying dangerous cargo like this would not be allowed into the harbor at all, but because of the war and German submarines, this rule was not being enforced.
When morning came, the Imo was given clearance to leave at around 7:30. Ships were restricted to 5 knots within the harbor, but the Imo was steaming well above that in order to make up for the delay. As it moved towards the ocean, the Imo met not one, but two ships going the wrong way; that is, ships were expected to keep right, and these ships were keeping left. This forced the Imo to make its way to the eastern end of the harbor, into oncoming ship traffic.
Meanwhile, at the mouth of the harbor, the Mont-Blanc made its move to enter as the submarine nets were lowered. The captain and the harbor pilot followed the directions, keeping to the righthand side of the channel, before the pilot noticed a ship on a dangerous course with them: the Imo. The Mont-Blanc attempted to signal the Imo that they had the right of way, but the Imo refused to yield its position. In response, Captain Le Medec ordered that the Mont-Blanc’s engines be cut and steered the ship to his right, towards the shore. Again, an attempt was made to signal the Imo, in the hope that it would follow suit and steer away from the shore, but again the Imo refused to yield. In the moments that followed, the Imo cut its engines as well, but the momentum of its earlier speeding carried it forward, closer and closer to the Mont-Blanc, whose crew couldn’t beach the ship for fear of setting off the explosives.
In one last attempt to avoid a collision, the harbor pilot on the Mont-Blanc ordered the ship to steer hard to the left, crossing the Imo’s bow and bringing the ships parallel with each other. For a brief moment, it appeared to work – until the Imo sent out a signal that it was reversing its engines. As the ship’s propellors suddenly spun in the opposite direction, the whole of the ship was briefly directed rightwards – right into the hull of the Mont-Blanc.
A Light Tap
The collision occurred at 8:45 AM, and caused superficial damage to the Mont-Blanc’s hull. Yet the force from the impact was enough to topple and rupture several barrels of benzol fuel on the deck, which spilled over and flowed into the hold where the explosives were kept. Then, as the Imo’s propellors reversed the ship, the scraping of the two ships’ hulls caused sparks which then ignited the spilled benzol, causing a fire in the water line that then spread up the side of the Mont-Blanc.
Captain Le Medec instantly knew what was going to happen, and frantically ordered his crew to abandon ship. As the crew entered their lifeboats and began to row away from what was now a ticking bomb, they noticed that nearby ships had stopped to spectate the fire. They tried to shout to them that the Mont-Blanc was going to explode; unfortunately, many did not hear them over the confusion. In addition to this, many Halifax citizens began to gather on the streets and by their windows to watch the burning ship in the harbor.
One ship, the tugboat Stella Maris, responded to the fire; interestingly, this boat was one of the two ships that the Imo had had to dodge only minutes earlier. Attempts were made to fight the fire, but the boat was not remotely equipped to handle this sort of crisis, and the ship backed off. The captain of the Stella Maris was in the process of working with other nearby ships to tow the Mont-Blanc away from the pier when the fire finally reached the ship’s cargo of high explosives, the culmination of the chain of catastrophe. Try to keep your bearings, because the numbers we’re about to throw at you are truly staggering.
Hell Raining Down
The explosion occurred at exactly 9:04:35 AM, almost twenty minutes after the initial collision. This exact time was determined using seismic records; just take a moment to think about that fact.
The Mont-Blanc’s entire cargo of high explosives detonated all at once, the explosion being the equivalent of about 2.9 kilotons of TNT. To put that into perspective, the “Little Boy” nuclear bomb, dropped on Hiroshima, was the equivalent of around 15 kilotons of TNT. A blast wave from the explosion radiated outwards at more than 1,000 meters, or 3,300 feet per second. At the center of the explosion, the temperatures reached upwards of 5,000 degrees Celsius (9,000 degrees Fahrenheit). A cloud of white smoke rose to at least 3,600 meters (11,800 feet/2 miles).
Such was the force of this explosion that the water in the harbor was completely displaced, exposing the seabed. Water then rushed back in to fill the gap, causing a tsunami that rose as high as 18 meters (60 feet) above the high-water mark of the harbor. This tsunami proceeded to carry multiple ships onto the nearby shore, including the Imo and the Stella Maris.
The Mont-Blanc was completely obliterated. The explosion blew the ship into thousands of pieces, sending white-hot shards of metal raining down on both Halifax and nearby Dartmouth, at the time a separate city. The forward 90mm gun of the Mont-Blanc was blown skyward and landed 5.6 km (3.5 mi) north of the explosion site. A part of the ship’s anchor, weighing half a ton, landed 3.2 km (2.0 mi) to the south.
Almost everything within a 2.6km (1.6mi) radius was either completely destroyed or badly damaged, with an area of over 400 acres being almost entirely scoured by the blast. Stoves and lamps were knocked over, starting fires throughout the city that would continue to burn for days afterwards. Factories were turned into heaps of rubble and the nearby dockyards were hit particularly hard, as were the train depots where over 500 railway cars were reported damaged. In total, over 12,000 buildings were damaged or destroyed by the blast.
Most of those buildings had people inside them at the time. Many were standing by their windows watching the fire when the explosion happened, shattering the windows and blinding them with flying glass; as many as 5,900 eye injuries were reported in the aftermath, with 41 suffering permanent loss of their sight. Workers in the factories were crushed by the collapsing buildings. Cadets and instructors at the nearby naval college were badly maimed. Sailors on ships near the Mont-Blanc were hit hard: the Stella Maris lost 21 of its 26 crew, with the captain perishing in the blast but his son, the first mate, surviving. The crew of the Mont-Blanc itself lost only one man.
One survivor, the firefighter Billy Wells, had his clothes torn from his body and thrown away from his fire engine by the force of the explosion. He described the scene he witnessed: “The sight was awful, with people hanging out of windows dead. Some with their heads missing, and some thrown onto the overhead telegraph wires.” All in all, the Halifax explosion would kill 1,600 people instantly, and injure over 9,000; 300 of those injured would die later. It was, without question, the worst man-made disaster in Canadian history.
Rescue efforts began almost immediately, with neighbors and coworkers making attempts to dig people out of collapsed buildings. Not long after, the surviving emergency services got involved, and after that anyone with a working car or truck was pitching in to help. The hospitals were quickly overwhelmed by the sheer number of wounded, with the Camp Hill military hospital admitting around 1,400 people in one day. Extra manpower was brought in from across Nova Scotia as efforts continued, including firefighters as far away as Amherst – 200 kilometers or 120 miles away.
Several ships near Halifax changed course to investigate and assist in rescue operations. One ship, the USS Tacoma, actually went to battlestations because they believed that they were being fired upon. Indeed, some survivors initially believed that the explosion was the result of a bomb dropped by a German plane, although that rumor quickly dissipated.
As if the initial disaster weren’t enough, a blizzard struck the area the very next day, dropping sixteen inches (41 cm) of snow on the ground, stalling trains with supplies and knocking down the telegraph wires. (They’d been knocked down before by the explosion, but hastily put back up afterwards.) Searches for survivors had to be called off; the one bright spot in the storm was that the snow helped put out the fires which were, at the time, still raging in the city.
The monetary cost of the disaster is only an estimate, but it stands at around 35 million Canadian dollars, which would be 591 million Canadian dollars today.
“Hold up the train”
The legacy of the Halifax explosion is one of breathtaking loss of life and damage. For a long time, the blast at Halifax was the singular explosive event that was used to compare other similar disasters to, including the atomic bombings of Hiroshima and Nagasaki. And while there is not much happiness to be gleaned from this disaster, we’d like to leave you with a somewhat more uplifting tale.
Before the explosion, as the Mont-Blanc was burning, a railway dispatcher by the name of Patrick Vincent Coleman was at his post at the railyard a mere 750 feet (230m) from the Mont-Blanc. He and his coworker learned from a fleeing sailor of the dangerous cargo on board, and they began to run for safety. However, as he ran, Coleman remembered that there was an inbound passenger train from New Brunswick, carrying around 300 people and due to arrive within minutes. Coleman turned around and returned to his post alone, where he sent an urgent 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.” Coleman would be killed by the explosion, but his message got through. Every train bound for Halifax was halted at a safe distance from the blast, including the passenger train at Halifax. It is a fact, then, that Mr. Coleman’s actions saved hundreds of lives that day; a hero, through and through.