At 9:04 a.m., the Mont-Blanc, loaded with over 2,600 tons of wartime explosives, detonated in Halifax Harbor after colliding with the Norwegian ship Imo. The blast leveled the Richmond district, killed approximately 2,000 people, injured 9,000 more, and blew out windows dozens of miles away. It remains the largest accidental explosion in history prior to the nuclear era.
The Mont-Blanc had sailed from New York bound for Bordeaux, packed with TNT, picric acid, guncotton, and benzol—a floating bomb making its way through wartime shipping lanes toward the trenches of the Western Front. As it entered Halifax's Narrows on the morning of December 6, it collided at low speed with the Imo, a Norwegian ship chartered for Belgian relief. The impact alone caused little damage, but it ignited barrels of benzol on the Mont-Blanc's deck.
Crew members, aware of the cargo, abandoned ship immediately and rowed frantically for shore, shouting warnings that most bystanders couldn't understand over the noise or simply didn't believe. The burning ship drifted toward the Halifax pier, drawing a crowd of curious onlookers, dockworkers, and schoolchildren who pressed against windows to watch the spectacle. At 9:04:35, it exploded with a force equivalent to roughly 2.9 kilotons of TNT, flattening the Richmond neighborhood, driving the ship's anchor shaft over three kilometers, and sending a shockwave that shattered glass in Truro, 100 kilometers away.
A tsunami-like wave followed, and a blizzard hit the ruined city the next day, hampering rescue efforts and burying survivors under snow. Roughly 2,000 people died, many of them children blinded by flying glass as they watched from windows. Boston sent relief trains within a day, forging a bond commemorated every year since when Nova Scotia gifts Boston a Christmas tree in gratitude.
Key people: Francis Mackey, Aimé Le Médec