About 10,000 to 20,000 people poured in to a place with a population of about 47,000 people. Canadian troops and supplies passed through the port on their way to Europe, while the injured were sent back to convalesce in city hospitals.
“The First World War sort of gave Halifax a renewed sense of purpose overnight,” Mr. Marsters said.
The colliding ships had both arrived from New York. There, under tight control, the French-owned Mont Blanc had been stuffed with an array of military explosives and had barrels of benzol, a volatile aviation fuel, added for good measure.
The Imo, from neutral Norway, had been chartered by a group founded by the future president Herbert Hoover and provided wartime food aid to Belgium. To try to ward off German U-boats, the Imo bore signs reading, “Belgium Relief” along its sides.
While passing through the only narrow section of the harbor, the Imo’s stern struck the Mont Blanc’s bow. The Imo was largely undamaged, but a fire broke out on the floating bomb that was the Mont Blanc. Its crew fled in lifeboats as the crippled ship drifted toward the Halifax shoreline.
The commotion soon brought out crowds in the largely working-class neighborhood along the narrows. Some survivors’ accounts described the immediate aftermath almost as if it were a fireworks display, with exploding barrels of benzol bursting in the sky. Many people, to their later harm, peered down at the harbor from the hillside neighborhood through windows.