Canadian history

The Halifax Explosion on the 6th of December 1917 remains the deadliest man-made disaster in Canadian history. The event is still considered the largest accidental non-nuclear detonation in recorded history. The disaster was caused by a harbour collision between the Norwegian vessel SS Imo and the French munitions ship SS Mont-Blanc, which was carrying high explosives for the Great War in Europe.

Patrick Willet Brock (PWB), a 14-year-old cadet at the Royal Naval College, witnessed the event and wrote about it in the journals he kept throughout his years at the naval college.

The sheer scale of the casualties was immense, particularly considering Halifax’s population at the time was only about 60,000. Nearly 2,000 people were killed—about 1,600 died instantly, and hundreds more succumbed to their injuries later. The dead included more than 500 children and 200 military personnel, many of whom were working at the dockyards. Approximately 9,000 others were injured, with hundreds blinded after watching the burning ship from their windows only to have the blast shatter the glass inward. Many others suffered ruptured eardrums and severe burns. But the crisis went on for days. They weren’t just dealing with the largest man-made blast of the pre-atomic age—they faced a merciless blizzard, a medical crisis, and a frantic search for answers in the wreckage.

The physical destruction was equally staggering.

• The Blast Zone: 325 acres (1.3 square kilometres) of the city’s North End were completely obliterated.
• Buildings: Over 12,000 buildings were damaged, with 1,630 of those completely levelled.
• Housing Crisis: 6,000 residents had their homes destroyed, and 25,000 were left with inadequate shelter.
• Economic Cost: Property damage was estimated at $35 million in 1917 ($700–$800 million today), though the modern replacement cost of the entire district—including docks, railways, and factories—would likely reach billions.

PWB wrote, “Outside points were most generous in their aid. As soon as possible. The injured were sent by train to Truro and other points, where the citizens were most kind to the sufferers. The way in which the United States sent their aid was very generous. Relief trains and ships were despatched.”

Truro, Nova Scotia, sent a relief train within the hour, while Moncton and Saint John dispatched firefighters, equipment, and medical personnel by rail that same afternoon. Prince Edward Island granted $8,000 for relief and sent a contingent of nurses to assist the city’s overwhelmed hospitals.

Perhaps the most famous assistance came from Boston, Massachusetts. Governor Samuel McCall did not wait for a formal request, immediately telegraphing, ”Understand your city in danger… Massachusetts ready to go the limit in rendering every assistance you may be in need of.”

The governor also did not wait for a reply. Before nightfall, a relief train loaded with doctors, nurses, and supplies departed Boston. This forged a bond between Nova Scotia and Massachusetts that remains strong over a century later. In gratitude, Nova Scotia sends a large Christmas tree to Boston every year. In 2025, a 45-foot white spruce was officially lit in the Boston City Common on December 4th, just two days before the anniversary of the explosion.