In 1917, two ships collided in Halifax harbor, resulting in the largest explosion in history up to that time.
"Hidden History" is a diary series that explores forgotten and little-known areas of history.
By December 1917, the First World War had been raging for almost three and a half years, and the Western Front was stalemated. England, France and Germany had nearly bled each other dry. The United States had declared war months earlier, but was completely unprepared for it and had yet to make any significant impact.
The Germans knew that Britain’s primary weakness was her utter dependence upon supplies from overseas, especially from North America. Canada was transferring large numbers of troops, and even before formally entering the war the United States had been sending food, clothing, manufactured goods and ammunition to England. In an attempt to cut off this vital supply line, the Kaiser had declared the sea lanes around the UK as a war zone, and announced that any ship entering this area would be subject to attack without warning by German submarines. So, to protect themselves from the menace of the hidden U-boats, American and Canadian shipping took to the practice of “convoys”, in which large groups of transport and cargo freighters would make their way across the Atlantic together, escorted by destroyers.
At the end of November 1917, the French freighter Mont-Blanc, captained by Aimé Le Médec, entered New York harbor. There she was loaded with a lethal cargo of explosives—over 2500 tons of picric acid, TNT, guncotton and benzol (a form of gasoline)—intended for the war effort. To avoid making her a specific target for the prowling submarines, she displayed no signal flags or any other warning that would indicate what she was carrying. And since she could not run the deadly U-boat gauntlet alone, when she left New York Harbor on December 1 (slinking out in the middle of the night to avoid any potential German prowlers offshore), she did not sail east for her home port of Bordeaux, but instead made her way north to Halifax, in the Canadian Maritime Provinces. There, she would join with an escorted convoy for the trip across the Atlantic.
The city of Halifax had been established by the Royal Navy in 1749 specifically to defend its Atlantic possessions from the French and had been a naval base ever since. When World War One broke out in 1914, it became the most important port in North America: almost weekly, convoys departed Halifax harbor carrying a seemingly never-ending procession of vital war supplies to England.
At around 4pm on December 5, the Mont-Blanc arrived at the mouth of the harbor, and a motor launch from shore delivered Francis Mackey, one of the harbor pilots at Halifax, to the ship’s bridge. Mackey was intimately familiar with the harbor, and it was his job to navigate the ship inside to a safe berth in the Bedford Basin, the deepwater portion of the port.
But Captain Le Médec had arrived just a short while too late. To protect the vital harbor from German U-boats, the entranceway was defended by a series of steel-mesh anti-submarine nets which were closed every night, and once these gates were shut, no ships could enter or leave the port. The Mont-Blanc would have to spend the night at sea and enter in the morning.
Meanwhile, another ship had been locked inside the harbor for the night. The Norwegian freighter Imo, commanded by Captain Haakon From, was empty: she was not a military ship but belonged to a civilian relief agency that used her to send food, medical supplies and other aid to war refugees in Europe. The Imo was on her way to New York to pick up a load of supplies, but she had been delayed by a re-coaling operation, and now she too was stuck inside the anti-submarine nets for the night.
When the submarine nets were opened again at 7:30am on December 6, the Mont-Blanc was second in line to enter the port. At the same time, the Imo got underway and sailed towards the harbor exit. The words “Belgian Relief” had been painted on her hull to try to avoid a German U-boat attack.
What happened next was later reconstructed from survivor accounts. At a point near the exit known as The Narrows, the Imo and the first freighter in line in front of the Mont-Blanc, the steamer Clara, entered at the same time. The rules of the navigational road were clear: ships were to pass to each other on the right-hand, or starboard, side of the channel, and ships that were coming into the harbor always had right-of-way over ships coming out. But now, both of these rules were violated. The Clara signaled to Imo that she wanted to pass on the left side in order to make an easier approach to her loading dock, and the Imo’s captain moved over to the opposite side of the channel. Captain From had intended to move immediately back to his proper lane once the other ship had passed, but as he tried to do so one of the harbor tugboats, the Stella Maris, entered the other lane towing two barges, blocking the Imo. Minutes later, the Mont-Blanc appeared, directly ahead.
Immediately, Captain Le Médec signaled with a single blast of his horn, meaning “Yield to me—I have the right of way”. Captain From on the Imo, still blocked by the tugboat, responded with two blasts, signaling “I am maintaining my course”. This resulted in a frantic exchange of whistle signals: nobody else knew the lethal cargo that the Mont-Blanc was carrying, but Captain Le Médec did, and he did not want to try to maneuver his ship in the channel and risk an accident. As the two ships approached each other, neither moved from their course, though both slowed down. At the last minute, the Mont-Blanc tried to make a sharp turn and the Imo tried to reverse engines, but it was too late. The two ships collided. It was 8:45am.
The damage from the impact was not extensive, but some of the benzol fuel aboard the Mont-Blanc leaked and started a fire. Captain Le Médec immediately recognized that a disaster was about to happen, and ordered his entire crew off the ship and into the lifeboats, where they frantically paddled towards shore. Here, they tried to tell somebody about the danger posed by the ship’s explosive cargo, but none of the French crew spoke English.
Meanwhile, nobody else knew the danger they were in, and ships rushed in to try to help with that they thought was just a routine fire. The harbor tug Stella Maris trained her fire-hose on the burning Mont-Blanc, while a pair of Canadian and British Navy ships moved in close to pick up people from the water. All around the harbor, townspeople gathered to watch the spectacle as a thick black cloud of smoke poured from the stricken freighter. The Mont-Blanc drifted ashore at Pier 6, and flames from the burning ship ignited the wooden pier as well. The city fire department responded with its brand-new gasoline-engined fire truck. Meanwhile, the Stella Maris and launches from one of the Navy ships tried unsuccessfully to tow the French ship away from the pier.
Captain Le Médec, by now, had been able to communicate to a number of people the danger that his ship presented, and word apparently reached the telegraph station on shore. Here, operator Vincent Coleman knew that the regularly-scheduled passenger train was about to arrive at any minute, and he frantically tapped out a message to the nearby railroad station to halt the train before it entered the danger zone. “Hold up the train,” he sent. “Ammunition ship afire in harbour making for Pier 6 and will explode. Guess this will be my last message. Goodbye boys.”
At 9:05am, the flames reached the explosives in the Mont-Blanc’s hold. With the force of over 2.5 kilotons—equal to a small tactical nuclear weapon—the ship went up in a brilliant white flash. The only recognizable portions of the Mont-Blanc that were later found were her anchor, blown 2.5 miles away, and one of her deck gun barrels, blown over 3 miles away. Ships 100 miles out at sea heard the low rumbling noise of the explosion.
Within a mile of the ship, everything was flattened by the blast wave, and windows were blown in as much as 60 miles away. The concussion was followed by a roaring wall of water that was pushed ahead by the explosion (the tsunami carried the Imo out of the harbor and beached her on shore). As buildings collapsed, fires were started in the rubble by wrecked stoves and fireplaces. Within hours, most of Halifax was a smoking ruin. At least 2000 people died in the blast or in its aftermath, and some 9000 were injured. The entire Richmond section of town was wiped off the map.
At first, with most people unaware that the French ship had been carrying explosives, it was assumed that the disaster had been the result of German sabotage at the port. All of the German-speaking residents remaining in Halifax were quickly rounded up and confined, and when a letter written in German was found on John Johansen, one of the surviving crewmen on the Imo, he was arrested too (he was then released when the letter was confirmed to be written in Norwegian, not German). It took most of the day for authorities to piece together what had actually happened.
The official inquiry in February 1918 concluded that the collision had been the fault of the Mont-Blanc, on the grounds that she alone knew what was in her cargo hold and it had therefore been incumbent upon her to take whatever steps were necessary to avoid an accident at any cost. Captain Le Médec and harbor pilot Mackey were promptly arrested for manslaughter. But no charges were filed, and a later inquiry placed the blame equally on both ships.
NOTE: As some of you already know, all of my diaries here are draft chapters for a number of books I am working on. So I welcome any corrections you may have, whether it's typos or places that are unclear or factual errors. I think of y'all as my pre-publication editors and proofreaders. ;)