The 1917 Halifax Explosion – One of the Biggest Maritime Disasters

Some of the devastation in Halifax, Nova Scotia after the December 6, 1917 explosion. (Courtesy HarperCollins/Nova Scotia Archives)

Halifax was devastated on December 6, 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 SS Mont Blanc, a French ship was arriving from New York City filled with munitions for World War I in Europe. In addition to the 2,925 tons of explosives in its hold, it carried barrels of highly flammable benzol and picric acid on the deck.

Unable to travel with its scheduled convoy across the Atlantic, the Mont Blanc went to Halifax so it could travel with a new group. It arrived the night before and had to wait outside the anti-submarine net that protected the harbour. At dawn, it began to move into the harbour. Normally, a munitions ship would fly a red flag to warn others of the dangerous cargo, but the Mont Blanc did not raise its warning flag.

Meanwhile, the SS Imo, a Norwegian ship carrying Belgian relief supplies that had been held up in the harbour for several days, began to move down the harbour toward the Atlantic. The Imo’s captain was angry because he had been delayed and so he put to sea without the harbour master’s permission.

The two ships were maneuvering for position as they met in the Narrows between Halifax on the southern shore and Dartmouth on the northern shore. Initially, the Imo refused to give way. Once it began to turn out of the Mont Blanc’s path, it could not move fast enough to avoid a collision. Barrels on deck broke loose with the impact, and sparks from the scraping metal ignited the benzol that had spilled across the deck. The Mont Blanc’s captain recognised the terrible danger of these fires and abandoned ship, rowing with the crew to the Dartmouth shore.

The damaged and burning Mont Blanc drifted to shore in the heavily populated wharf area of Halifax. Crowds gathered on the shore and at windows to watch the burning ship run aground. Barrels of benzol began to shoot into the air like fireworks and explode. Approximately 20 minutes after the collision — at 9:04 a.m. — the fires ignited the 2,925 tons of munitions on the Mont Blanc and the ship exploded. The ship was vaporized instantly, a huge area of Halifax was destroyed, and an enormous debris cloud rose over the city.

What followed was one of the largest human-made explosions 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.

Many safety-related changes were made after the Halifax Explosion, including new rules for storage of hazardous materials and harbour navigation.

The Halifax Explosion revealed many inconsistencies and disparities in the routing of naval traffic, shipping signs and signals, and the transportation of dangerous goods. This event resulted in strict, uniform shipping lanes and water traffic management becoming standard throughout the world. The study and safe handling of high explosive – especially the highly unstable picric acid – advanced rapidly.

While explosions and mishaps continue to happen, despite observing safety precautions, it is important to reflect on incidents such as these to understand why these measures were put in place in the first case. The Halifax disaster is a haunting reminder of the devastation that can be caused by accidents and begs caution when navigating and handling cargo that is dangerous.

References: University of Virginia, The Star, Atropedia, The Canadian Encyclopaedia 

Sea News Feature, March 7