December 6, 1917
Halifax, Nova Scotia
Two ships collide in the harbor, causing a massive explosion resulting in the deaths of over 1,800 people and wounding over 9,000

Traffic was congested in the harbor on December 6, and the SS Imo, a Norwegian vessel carrying supplies for the Belgian Relief Commission, had to navigate around a tow boat. In doing so, the Imo was placed in the path of the SS Mont-Blanc, a French cargo ship transporting 2,925 metric tons (about 3,225 US tons) of explosives — including picric acid, trinitrotoluene (TNT), high-octane gasoline, benzole (a highly combustible motor fuel), and nitrocellulose (guncotton) — to Europe to aide in the war efforts of World War I.

The vessels issued warning signals to the other and took evasive action to avoid a collision, but were unable to avoid impact. The ships scraped against each other at approximately 8:45 a.m., causing sparks which ignited the flammable materials, either the picric acid or the benzole, on the Mont-Blanc.

The crew of the Mont-Blanc immediately abandoned ship and attempted to alert the harbor of the dangers of the burning cargo ship filled with explosives. The Mont-Blanc bore no markings to indicate it was hauling munitions and the crew spoke only French, a language spoken by few people in Halifax at the time, and so those in nearby vessels or on the harbor were unaware of the imminent danger.

Spectators gathered to watch the burning ship which soon ignited the harbor as it moved past. The fire department arrived at approximately 9:05 a.m. and, as the firefighters were preparing to connect to a fire hydrant, the Mont-Blanc exploded in a “blinding white flash,” the explosion ripping through the ship at 1,500 meters per second (4,900 feet/second).

A view of the smoke plume from the explosion
via Britannica

Frank Baker, a Royal Navy sailor aboard the HMCS Acadia, wrote of the disaster in his diary on the day it occurred. Baker and others on the Acadia were assembling tools for cleaning “when the most awful explosion I ever heard or want to hear again occurred. … Our first impression was that we were being attacked by submarines, and we all rushed for the upper deck, where we saw a veritable mountain of smoke and a yellowish hue and huge pieces of iron were flying all around us. … A tug was alongside us at the time and part of her side was torn completely out and three of the crew were injured, one of them getting a piece of flesh weighing nearly 2 pounds torn off his leg. … One ship had been hurled wholesale for a distance of about 400 yards, dashing it close to the shore, a total wreck with dead bodies battered and smashed lying all around in disorder. … What a few hours before had been beautiful vessels, were now terrible wrecks, their crews all dead and bodies, arms, etc. were floating around in the water. The town was literally ablaze, the dry dock and dockyard buildings completely demolished and everywhere wounded and dead. The theatres and suitable buildings were all turned into hospitals and shelters for the accommodation of the homeless. … Poor little kiddies homeless, their parents having perished, were crying piteously and anxious relatives were inquiring for their dear ones. … For miles around nothing but a flaming inferno, charred bodies being dragged from the debris and those poor devils who were left still lingering were piled into motor wagons and conveyed to one of the improvised hospitals.”

Some 200 people were blinded by the explosion; ophthalmologist George Cox alone enucleated 79 irreparably damaged eyes within 48 hours. The shockwave generated from the explosion shattered windows 50 miles (80 km), and the sound could be heard from hundreds of miles away. The Imo was pushed ashore where it was grounded. Debris from the Mont-Blanc rained down over an 8-kilometer (5-mile) radius, including the shaft of the ship’s anchor, weighing 1,140 lbs. (517 kg), which impaled the ground 2 miles (3.2 km) from where the vessel once was.

The explosion also triggered a tsunami approximately 60 feet (18 meters) high, which pressed 3 blocks inland, destroying 1,600 homes, decimating a centuries-old Mi’kmaq fishing settlement, and dragging debris over several miles. Complicating the relief effort, a blizzard set in on the area the following morning, producing wind gusts reaching 90 km/h (56 mph) and wind chills of -15ºC (5ºF), and eventually covering the area with 40 centimeters (15.75”) of snow.

Between the explosion, the tsunami, the falling debris, and the blizzard, over 1,800 people were killed and a further 9,000 injured.

“Halifax Explosion.” Maritime Museum of the Atlantic. Accessed: December 6, 2020.
“The Great Halifax Explosion.” History. Accessed: December 6, 2020.
“Halifax explosion.” Britannica. Accessed: December 6, 2020.
Hendrix, Steve. “Two ships collided in Halifax Harbor. One of them was a floating, 3,000-ton bomb.” The Washington Post. December 6, 2017. Accessed: December 6, 2020.
“Why a nasty snowstorm following the Halifax Explosion came as a surprise.” CBC News. December 4, 2017. Accessed: December 6, 2020.
Wortman, Marc. “A Newly Discovered Diary Tells the Harrowing Story of the Deadly Halifax Explosion.” Smithsonian Magazine. July 14, 2017. Accessed: December 6, 2020.

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