At 9.04am on 6th December 1917, a collision between two ships in Halifax harbour, Nova Scotia, resulted in an explosion that killed more than 1,900 people and wounded 9,000.
The Mont-Blanc was a French cargo ship manned by French sailors under the command of Captain Aime Le Medec. She steamed out of New York on 1st December 1917 packed with explosives destined for the Western Front.
Her course took her first to Halifax, where she was due to join a convoy across the Atlantic.
In her holds were over 2,000 tons of picric acid (similar to TNT, used from the late 19th century), 250 tons of TNT, and 62.1 tons of gun cotton. In addition, some 246 tons of benzoyl sat in barrels on the deck.
Under normal circumstances, a ship carrying explosive munitions would fly a red flag as a warning. The threat of U-Boat attack meant the Mont-Blanc had no such flag.
The Imo, under Captain Haakon From, was chartered by the Belgian Relief Commission. She arrived at Halifax on 3rd December from Rotterdam and was due in New York to load relief supplies.
Confusion in the harbour
On the morning of 6th December, the Imo steamed out of the Bedford Basin into The Narrows between Halifax and Dartmouth, which lead out into the Atlantic Ocean.
At around the same time, the Mont-Blanc approached The Narrows from its anchorage just outside the harbour’s submarine nets.
Disaster struck when the Mont-Blanc was led into the wrong channel in The Narrows, on the Dartmouth side rather than the Halifax side. The Imo was already in the Dartmouth channel heading through The Narrows toward the Mont-Blanc.
In an attempt to switch channels, the Mont-Blanc turned to port, leading it across the bow of the Imo. Aboard the Imo, Captain From ordered a full reverse. But it was too late. The bow of the Imo crashed into the hull of the Mont-Blanc.
The collision caused the barrels on the Mont-Blanc’s deck to topple over, spilling the Benzoyl that was then ignited by the sparks from the two hulls grinding together.
With the Mont-Blanc quickly consumed by flames, Captain Le Medec ordered his crew to abandon ship. Captain From ordered the Imo to head out to sea.
The people of Dartmouth and Halifax gathered at the harbour-side to watch the dramatic fire as it puffed thick plumes of black smoke into the sky. The crew of the Mont-Blanc, having rowed to the Dartmouth shore, couldn’t persuade them to stay back.
The Mont-Blanc drifted toward Halifax, setting fire to Pier 6. Minutes later, she exploded.
The blast and the recovery
The detonation, equivalent to 2989 tons of TNT, threw out a powerful blast wave that tossed debris high up into the sky above Halifax. Part of the Mont-Blanc’s anchor was later discovered two miles away.
Temperatures at the moment of detonation reached 5,000 degrees Celsius, causing the water in the harbour to vaporise, resulting in a tsunami. The Imo, racing to escape the scene, was smashed against the shore. In the city, clothes were ripped off the wearers’ backs by the blast.
Spectators were blinded by shattering windows. More than 1600 people were killed instantly and every building within a 1.6-mile radius was destroyed or badly damaged. In the chaos, some believed the city had been attacked by German bombers.
Temporary housing was required for the approximately 8,000 people made homeless. In January 1918 the Halifax Relief Commission was set up to oversee the ongoing relief effort.
In the immediate aftermath, rescue efforts were hampered by a lack of coordination. But the people of Halifax pulled together to rescue neighbours and strangers from the rubble and to transport the injured to medical centres.
Hospitals were soon overwhelmed but as news spread of the disaster supplies and extra medical staff began to stream in to Halifax. Among the first to send aid was the state of Massachusetts, which sent a special train packed with critical resources.
Nova Scotia presents Boston with a Christmas tree each year in recognition of this assistance.
In the days and months after the blast, countries around the world donated money to help with the rebuilding programme.
Header image credit: A view across the devastation of Halifax two days after the explosion, looking toward the Dartmouth side of the harbour. Imo is visible aground on the far side of the harbour. Credit: Commons.