On a crisp December morning in 1917, Halifax Harbor was bustling with wartime traffic. The SS Mont-Blanc, a French cargo vessel crammed with over 2,900 tons of high explosives including picric acid, TNT, and highly flammable benzol fuel, was creeping into the harbor to join a transatlantic convoy. At the same time, the SS Imo, a Norwegian relief vessel, was departing at an unsafe speed, attempting to make up lost time.
As the ships approached the Narrows—a constricted strait connecting the outer harbor to Bedford Basin—they found themselves on a collision course. Misinterpretations of whistle signals and stubborn refusal by both captains to yield the right-of-way led to a fatal game of maritime chicken. At 8:45 AM, the Imo struck the starboard bow of the Mont-Blanc at low speed.
The physical damage was minor, but the collision ruptured drums of benzol stored on deck. Sparks ignited the volatile vapor, creating a raging fire that the Mont-Blanc's crew could not extinguish. Knowing their cargo, the terrified French sailors abandoned ship, shouting warnings that were unheeded by observers on shore who mistook the commotion for a routine ship fire.
Abandoned and burning, the vessel drifted toward Pier 6. At 9:04 AM, the fire reached the main hold. The resulting blast detonated with an estimated energy equivalent of 2.
9 kilotons of TNT. The shockwave flattened 800 hectares of Halifax, sent a 60-foot tsunami washing over the shore, and shattered windows 60 miles away. Nearly 2,000 people were killed instantly, with another 9,000 injured, making a tragic failure of basic maritime navigation one of the most destructive industrial disasters in human history.