The worst accident in history - the Halifax disaster

It was the largest man-made explosion in history up to that time, and the largest unintentional explosion in history since then.

The amount of explosive material used in a terrorist attack is usually limited: it is difficult to accumulate, hide and then transport large quantities of such problematic materials. This limitation does not affect armies and governments - which is the reason why accidents involving explosives are much more dangerous and destructive than terrorist attacks - as the Canadians learned firsthand, at the beginning of the twentieth century.

The city of Halifax in Canada was a very important logistical center for the Allies in the First World War. One of the main reasons for this was the structure of its port: the anchorage was hidden deep within the continent and to enter it one had to pass through a narrow channel known as 'The Narrows'. The narrow channel protected the anchorage from enemy submarines and therefore the port in Halifax attracted ships from all over the world.

One of those ships was the French merchantman 'Mont-Blanc'. Montblanc arrived in Halifax on Thursday, December 1917, late at night - but could not get inside. The gates of the harbor were closed every night to ship traffic as a defense against submarines, and Mont-Blanc had to drop anchor outside the harbor. Early the next morning the crew rushed to sail the ship to the port. They had good reason to hurry: Mont Blanc was loaded with several thousand tons of explosives of all kinds, including about 200 tons of TNT.

The TNT came into use in the major armies a few years earlier, and was a dramatic development in military history. Its important feature, for military applications, is that it turns into a liquid at a relatively low temperature - so it can be poured into shells and shaped into the desired shape.

At that time, a Belgian merchant ship named 'Imo' left the port, on its way to New York to collect food and supplies for Europe.

As the emo approached the narrow area of ​​the Narrows it noticed a third ship also making its way into the canal. Nautical laws state that two ships sailing towards each other must turn right, in order to pass each other on the left side. In this case, the ship that entered the port had to turn to the left in order to dock at the wharf, so the captain of the Imo and the captain of the ship in front of him decided to violate the established practice consciously and by mutual agreement, in order to allow the other ship more convenient access to the wharf. They passed each other on the right side, and the result was that at the end of the maneuver the Imo was close to the left bank of the canal - in nautical terms, she was on the wrong side of the road. Moreover, the emo sailed fast - too fast, it seems, than the normal speed in a narrow channel.

Just at this moment Montblanc also entered the narrow canal. Her captain noticed her mother approaching towards them, and blew one horn for her. One whistle means 'I want to pass you on my left side', and translated to a non-sailor - 'This is my lane, idiot, go back to yours.'

The captain of the Imo refused to change his course. Maybe he thought he was sailing too fast and wouldn't be able to turn right in time. Perhaps he was hoping that Mont Blanc's captain would be nice enough to clear the way for him. Maybe he was just being a bully. We will never know because twenty minutes later he and most of the Imo's crew were gone.

The mother honked twice, signaling to Mont-Blanc that she intended to stay in the lane and that Mont-Blanc was being asked to turn left. A frantic siren communication was conducted between the two ships to try and resolve the entanglement, but within a few minutes the two captains realized that if they did not do something quickly, the collision would be inevitable.

Mont-Blanc broke sharply to the left, towards the center of the canal. The emo swung her propellers back to brake, but this braking caused her bow to veer to the right, also toward the center of the channel.

At eight-thirty in the morning, a crowd of Blanc and Emo clashed. Metal hit metal and sparks flew everywhere. A fire broke out on board the Moun Blanc.

Montblanc's crew initially tried to put out the fire, but when the sailors realized the fire was out of control, they hurried to abandon ship. While rowing in the lifeboat and away from the burning barrel of explosives that was their ship, the French sailors shouted to the crew of the emo that the ship beside them was a death trap from hell. Unfortunately, no one on the Imo - whose sailors were mostly Norwegian - knew French. In addition, Mont Blanc carried no flag, sign or other marking to warn of the deadly charge now burning on board.

The Halifax port authorities, who also had no idea of ​​the extent of the trouble, sprang into action. Fire boats were sent to spray water on Mont-Blanc and rescue teams were concentrated on the docks, ready to take in casualties if there were any. Hundreds of curious spectators gathered on both banks of the canal.

In the meantime, the sailors of Mont-Blanc managed to reach a safe beach and fled as long as they could, hoping to get away from the place as fast as their legs could carry them. On the way they passed by a train station and met Vince Coleman, one of the inspectors. They managed to explain to him what it was about and Vince began to run away as well. A moment later, however, the inspector remembered that in a few minutes a train loaded with hundreds of passengers was supposed to enter the station. He hesitated, then turned back and ran back into the office.

At nine and four minutes Mont-Blanc exploded. It was the largest man-made explosion in history up to that time, and the largest unintentional explosion in history since then.

TNT is an explosive of the 'crushing' type - HANAM, for short. The source of its power lies in the breakdown of the molecule that makes up the explosive. This process, known as 'detonation', creates a tremendous shock wave that passes through the central nervous system at a speed of up to eight kilometers per second, with each molecule that disintegrates releasing energy that causes the disintegration of its neighbor, and so on. The shock wave created as a result of the rapid expansion of the hot gases is the one that causes the most damage as a result of the shattering of the Hanam.

Two square kilometers of urban area near the harbor were completely flattened. The damage was so complete that people who had lived there all their lives could not recognize the place where their house once stood. 1500 people were killed where they stood. The shock wave of the explosion, whose strength was about one-fifth that of the bomb dropped on Hiroshima, shook ships sailing in the sea at a distance of about thirty kilometers. Part of Mont Blanc's anchor, a piece of metal weighing about half a ton, was blown four kilometers away.

The intense explosion raised a tsunami wave 18 meters high that washed over both sides of the canal. People who survived the explosion itself drowned under the raging water, too stunned to try and save themselves. All over Halifax, gas lamps and stoves that heated the houses in the cold December fell, and huge fires consumed entire neighborhoods. Another five hundred people were killed in the fires.

About nine thousand people were injured in varying degrees of severity. One of the most common injuries was an eye injury: many watched the firefighters' efforts through the windows of their homes when Mont-Blanc exploded, and the glass fragments from the windows injured hundreds of people. Dozens of them were permanently blinded. In the years that followed, Halifax became a world center for the treatment of eye injuries as a result of the relatively high percentage of the population that suffered from them.

Vince Coleman, the train inspector, was killed in his office - not before he had time to send panicked messages to all incoming trains and order them to stop. The lives of hundreds of passengers were saved thanks to the heroism and supreme sacrifice of one railway inspector. Coleman is today considered one of Canada's greatest heroes.