In many ways it was a typical early winter day in Halifax – that December 6, 1917. The sun was bright in a clear sky and the ground was clear of snow. A light haze hung over the harbour but visibility was generally very good.

But what started out as a typical day did not end that way. No – that day became the most notorious day in the history of Halifax. That’s the day of the Halifax Explosion.

The Halifax Harbour is considered to be one of the finest and safest harbours in the world. Reaching far inland from the Atlantic Ocean it is protected not only from the fierce ocean but also, and most important in times of war (remember the date?… the First World War was still raging in Europe.), protected merchant ships from the marauding German U-boats. Because the war effort included shipping of large amounts of material to Europe, and because of  its strategic location in North America, Halifax became the staging point for many trans-Atlantic convoys.

One ship which arrived to the Halifax Harbour was the Mont Blanc. She arrived from the New York Harbour too late on December 5 to enter the harbour that day. (In the early evening the harbour-master raised a large chain across the mouth of the harbour to keep out U-boats.) At 07:30 on the 6^th she raised anchor to sail inland.

At the same time as the Mont Blanc sailed in, a second ship – the Imo - prepared to leave port and head to the open ocean.

The Mont Blanc, a French steamer, was 330 feet long and 40 feet wide. Her cargo of explosives was bound for the fighting in Europe by way of Bordeaux, France. And what a cargo it was…! The manifest of the Mont Blanc reads like a chemistry experiment:

• 2300 tons of wet and dry picric acid;
• 200 tons of TNT;
• 35 tons of benzol (stored on the open decks); and
• 10 tons of gun cotton.

You want to believe that there were more than a few no-smoking signs on that ship!

The Imo, 430 feet long and 44 feet wide, was heading for New York after its trip from Holland. She traveled as a neutral vessel and had no explosive material or guns on board.

(You can read more about the details of why these two ships collided on that fateful day in December. Our role at Mysteries of Canada is to highlight the story not the details.)

Through a series of mixed signals, the Imo appeared to be sailing in the approach right-of-way (in other words, the wrong lane) moving quickly toward the Mont Blanc. The Mont Blanc gave a short blast of its signal whistle to let the Imo know that it (the Mont Blanc) had the right-of-way. The Imo, to the surprise of the Mont Blanc, signaled its intention to turn to port, putting it further into the path of the Mont Blanc. A flurry of more signals ensued and eventually the collision to place mid-stream right next to one of the busiest wharves in Halifax.

The collision ruptured the benzol barrels on deck and caused a leak into the hold containing the picric acid. A fire began, spewing thick black smoke into the clear sky.

Knowing the fate of the Mont Blanc, the captain and crew abandoned ship and rowed to the Dartmouth shore. The Imo was only slightly damaged and, not knowing the cargo on the Mont Blanc, its crew remained with the ship.

At 09:05 the Mont Blanc exploded with the power of a volcano. 3000 tons of steel shattered and a mini-tidal wave fanned out from the spot. The explosion was so violent that a one of the Mont Blanc's guns flew over 3.5 miles before coming to rest in Dartmouth. An anchor, weighing 1140 pounds landed some 2 miles away at Armdale.

The toll of the Halifax Explosion was enormous with over 1600 men, women and children killed. An additional 9000 people were injured and  25,000 buildings spread over 325 acres were destroyed.

Communications links with the outside world were destroyed by the explosion which made the relief effort even more difficult.  Click the thumbnail at the left to see one of the few messages that got out.

We encourage you to read about this great Mystery of Canada.