At that time the Halifax Harbour is considered to be one of the 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 (check back the date), from the sneaky marauding German U-boats. But war is mostly a good business and the war effort included the shipping of large amounts of material to Europe. Because of its strategic location in North America, Halifax became the staging point for many trans-Atlantic convoys.
One ship which arrived in Halifax Harbour that day was the Mont Blanc. The vessel arrived too late from New York the day before and could not enter the harbour on December 5th due to harbour regulations and because a large chain was raised across the mouth of the harbour to keep out U-boats. Those who arrive too late watch the safest harbour in the world from the outside and are left to themselves for a cosy night with the Germans. Anchor is raised on the Mont Blanc at 07:30 on December 6th to enter the harbour.
At the same time as the Mont Blanc sailed in, a second ship, the Imo, prepared to leave port and was heading to the open ocean. So far, so good...
- 2300 tons of wet and dry picric acid;
- 200 tons of TNT;
- 35 tons of benzol (stored on the open decks - no fear);
- 10 tons of gun cotton;
- probably 1000 'no smoking' signs
On myyy left siiiiiide, the Imo, 130 m long and 17m wide, was heading for New York after its trip from Holland - traveled as a neutral vessel and had no explosive material or guns on board. Only Dutch weeds probably if you take a look at the way the crew behaved...
After and despite a series of mixed signals, the Imo appeared to be sailing in the approach right-of-way (the wrong lane for ships) moving quickly toward the Mont Blanc. The Mont Blanc gave a short blast of its signal whistle to let the Imo know that it had the right-of-way.
To the surprise of the Mont Blanc captain, the Imo signaled its intention to turn to port, putting it even further into the path of the Mont Blanc. A flurry of more signals ensued and eventually the collision took place right next to one of the busiest wharves in Halifax - damn psychadellic weeds!!
Knowing the fate of the Mont Blanc, the captain and crew abandoned ship immediatly and rowed to the Dartmouth shore - quickly! After a short time nobody on the shores could ignore the spectacular fire. The Imo was only slightly damaged and, not knowing the cargo on the Mont Blanc, its crew remained with the ship while the Mont Blanc was drifting in the harbour.
On that day at 09:05 the largest man-made pre-nuclear age explosion was recorded. The Mont Blanc exploded with the power of a volcano. A blast of 3000 tons (for the geeks: 1.26 x 10exp13 Joules), a fire ball of 1900 m (yes, 1,9 km), a tidal wave of 18m fanning out from the spot in every direction.
The explosion was so violent that parts of the ship were raining all over the city. One of the Mont Blanc's guns flew over 5.5 km before coming to rest in Dartmouth. An anchor (see picture below), weighing 517 kg landed over 3 km away in Armdale. A couple of memorials can be found in (and around) Halifax today to recall this memorable catastrophe. They are mostly made of parts of the Mont Blanc that landed there.
Some later studies revealed that the Halifax Explosion had damaged buildings and shattered windows as far away as towns like Sackville on Windsor Junction... about 16km away. Buildings have been reported to have shaken and items to have fallen down from shelves or tables in towns as far away as 126 km. The blast could still be felt in some places up to 360 km away.
Large scale manufacturing and transportation of amunition during the 20th century lead to a series of accidents that trigged massive explosions. In 1994, a team of scientists and historian published an extensive comparison of 130 major artificial explosions. This report concluded that, 'The Halifax Harbour Explosion remains unchallenged in overall magnitude as long as five criteria are considered together: number of casualties, force of blast, radius of devastation, quantity of explosive material, and total value of property destroyed.'
You can view a list of some of some of the largest man-made non-nuclear exloisions HERE.