The Halifax Explosion: 100 Years

December 06 2017

On this day exactly 100 years ago, life for the residents of Halifax and surrounding areas was irreparably changed, when the Halifax Explosion obliterated our fledgling, yet bustling, harbour city.

On December 6, 1917, in a series of events that would seem farfetched if scripted in a movie, the French cargo ship SS Mont-Blanc collided at low speed with the Norwegian SS Imo in the Narrows of Halifax Harbour due to a series of initially innocuous, and then eventually disastrous decisions by the crews of each respective vessel. Each vessel faced a series of delays, route changes, critical decision-making, and coincidences that all combined to ensure the fateful morning collision between the Mont-Blanc and the Imo.

With World War I still underway, Halifax Harbour was a busy international hub for the Allied war effort. The SS Mont-Blanc arrived in the Harbour from New York on December 5th, and was scheduled to travel to Bourdeaux, France with a convoy to deliver its full and highly volatile cargo of TNT, picric acid, benzol, and guncotton. However, as it was war time, anti-submarine nets (in place due to the ongoing fear of a German submarine attack) had already been raised at the neck of the Bedford Basin, preventing the Mont-Blanc from entering – as such, the vessel waited outside the harbour overnight for its turn to enter in the morning.

The SS Imo was also in Halifax Harbour for the war effort, as it had sailed from the Netherlands en route to New York to load up relief supplies for the starving citizens of Belgium. However, delays in Halifax with getting refuelled and receiving its load of coal meant that the Imo sat in Halifax Harbour for two additional days as it fulfilled its cargo stockpiling mission. The Imo was finally permitted to leave Halifax Harbour the morning of December 6th.

At approximately 7:30am on December 6th, the Mont-Blanc began slowly entering the Harbour after its wait outside the Harbour the previous evening. Shortly thereafter, the SS Imo began its already-delayed departure from the Harbour, traveling well above the Harbour’s speed restriction of 5 knots in an ill-fated attempt to make up for two days of delays and lost time. During the Imo’s trip out of the Harbour, it encountered the SS Clara, an American steamer traveling on the wrong side of the Harbour (ships were supposed to keep to the right, much like driving, passing each other port side to port side – the Clara was traveling on the left). Both pilots agreed to pass each other starboard to starboard (each on their respective left-hand side of the Harbour), and continued on their way.

Very shortly after, with the Imo still on the wrong side of the Harbour, it encountered a tugboat, the Stella Maris, that was traveling in the middle of the Harbour. This essentially forced the Imo to keep going on the wrong side of the Harbour, keeping it on that path and on a potential collision course with the Mont-Blanc. The Mont-Blanc’s pilot, Francis Mackey, saw the Imo was in its path approximately ¾ of a mile away, and concern grew that a collision may occur. As the Mont-Blanc was in the right-of-way, Mr. Mackey gave two horn blasts in an attempt to have the Imo yield – the Imo returned with two horn blasts of its own, indicating it would not (or could not, likely due to its excessive speed leaving the Harbour) yield to the Mont-Blanc. Despite attempts at evasive maneuvers, both ships collided at slow speed.

The collision did not result in an instantaneous explosion. The Imo hit the Mont-Blanc, tearing into its side, and knocking over barrels of extremely flammable benzol. As the Imo attempted to extract itself from the Mont-Blanc’s hull, metal-on-metal grinding between the vessels created sparks that ignited the benzol vapours, resulting in a rapid spread of uncontrollable fire and flames aboard the Mont-Blanc.

Crowds gathered on the harbourfront to watch the flaming ship, as the crew scrambled to get into their lifeboats. Nearly everyone witnessing the remarkable wreck was oblivious to the fact that the Mont-Blanc was a massive bomb waiting to blow – as the Mont-Blanc’s crew scrambled into their lifeboats to escape, their French-language cries warning everyone of the ship’s explosive contents were lost in translation and the chaos. The Mont-Blanc was not marked with any flags as holding explosive cargo, as doing so in wartime makes them an obvious target to enemy fire. In hindsight, revealing this critical information may have saved hundreds of lives, as fearless firefighters, police, first responders, and citizens of Halifax rushed to help the crew and anyone else impacted as the ship continued to go up in flames, completely unaware of its deadly payload.

At approximately 9:04am, 19 minutes after the collision between the Mont-Blanc and the Imo, one of the worst disasters in Canadian history was complete: the Mont-Blanc exploded, the sheer force launching its 90mm gun 5.6 kms (3.5 miles), and the shank of its ½ ton anchor 3.2 kms (2.0 miles) away, while levelling nearly everything and everyone within an 800 metre (1/2 mile) radius of the blast. It was, at the time, the largest manmade explosion ever experienced on earth.

It is still hard to fathom the devastation. 1,600 people were killed instantly. 9,000 more were injured, 300 of whom later died from their injuries. Hundreds upon hundreds of people were blinded by shattered windows caused by the blast’s shockwave. 548 buildings burned. 824 buildings collapsed. 1249 buildings wrecked. Virtually nothing left of a city with a then-population of 60,000.

The response and rescue efforts after the explosion came from far and wide: Massachussetts, New York, Rhode Island, Maine, and beyond all sent relief and supplies. In our industry of critical information and communications, it is easy to take for granted the modern-day technologies in place to help mitigate the effects of a disaster such as the Halifax Explosion. 100 years ago, instant critical communication infrastructure consisted of horns, sirens, and telegraphs. Heroes of public safety, military, and the general public risked and lost their lives, as they still do today despite our advances in technology.

One such hero was Vince Coleman, a railyard dispatcher in Halifax during the explosion. When Vince learned of the explosive contents of the Mont-Blanc, he began to leave railyard to save himself. But before Mr. Coleman left, he remembered that a train loaded with passengers from Saint John, New Brunswick was scheduled to arrive at the Halifax train station within minutes. Thinking of only those passengers, Mr. Coleman returned to his post, and sent the final telegraph of his life in an attempt to warn the incoming train. That train from Saint John indeed heeded Mr. Coleman’s telegraphed warning, saving hundreds more lives. A secondary impact of Mr. Coleman’s all-points-telegraph was that it allowed surrounding communities in Nova Scotia and beyond to prepare for the influx of wounded and dying people coming their way. Immediately after sending that final telegraph, the explosion killed Mr. Coleman. His 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."


At 9:04 am today, we will be taking a moment to remember all the souls lost during the Halifax Explosion, and all the brave first responders and citizens who selflessly risked and sacrificed their own lives to save those in need.

Back to blog