On 6 December 1917 the largest manmade explosion in the history of the earth (to that point) took place, not along the lines of battle, but in a busy Canadian seaport, Halifax, Nova Scotia. The blast came from munitions materials contained in a single average-sized (for 1917) freighter, and have been calculated to have been about equivalent to 2.9kt — larger than some nuclear warheads, and one of the top five known conventional explosions in history. (The Daily Mail has a table of seven big ones).
Ground zero of the Halifax Explosion. Pier 6 was located at this point; it has vanished without a trace. The shattered tug is the former minesweeper Stella Maris; she took the abandoned, burning Mont Blanc under tow. All but five of her 25 officers and men died. (Old photo. Source).
Recently, long-lost images from the aftermath of the explosion that destroyed or seriously damaged nearly 14,000 buildings, leveled the shipyard, and killed perhaps 2,000 people, surfaced in England. Here’s a half-minute look at the devastation on video:
The “new” pictures were taken by Lieutenant Victor Magnus, RN (or RNR/RNVR?), about 27, whose w ship was docked in the port city at the time of the event. The Daily Mail explains how the pictures were recently rediscovered in an old album by the photographer’s daughter, nearly 100 years after they were taken. The Halifax Chronicle-Herald notes that Magnus was standing watch in HMS Changuinola, whose log notes, among many other entries:
Other: 8.50 Explosion in docks followed by fires
Other: 9.15 Cutters away with officers ~~ to help ashore
Changuinola was an “Armed Merchant Cruiser” — a term for merchant ships put to military use in the RN. Specifically, she was a seized German ship pressed into service as a patrol and escort vessel, and apparently also to train RNVR officers or ratings (training these men frequently recurs in the ship’s logs). From her decks, Magnus took pictures like this:
Some of Magnus’s photos show the explosion’s pillar of smoke. No pictures from so soon after the blast were imagined to exist.
Then he went ashore. There he took more images of the appalling destruction.
Near Ground Zero, Halifax side looking towards Dartmouth side, Magnus photo.
Magnus was an avid photographer, and worked in maritime insurance before and after the war.
Victor Magnus in his naval uniform.
Historic Background (and more old photos)
The French ship Mont Blanc had just been loaded with a cargo of high explosive in New York: over five million pounds of explosives and inflammables, most of it highly unstable picric acid (Benzol, an octane booster then used in aviation fuel, and guncotton, a primitive explosive, were also aboard). Mont Blanc intended to join a convoy from Halifax to England, but on its way in to the harbor collided with an empty vessel, Imo, that normally ferried humanitarian aid to Belgium. Imo, with a Norwegian crew, was wrong-side-driving out of the harbor as Mont Blanc stood in, on the normal inbound side of the channel.
SS Imo. The foreground is not only devastated by the blast, but also by tsunami. Old photo. Source. There’s no post-disaster photo of the hazmat ship SS Mont Blanc; pieces of her fittings landed miles away.
The crew and harbor pilot of Mont Blanc abandoned ship and fled when their hazardous cargo took fire; the ship drifted to land, drawing curious onlookers, then exploded. The city was devastated, especially the shoreline, the shipyards and docks, and other ships making ready for the next England convoys on the 7th and 11th (a single convoy would leave on the 11th).
Most of the convoy ships were in Bedford Basin, the most protected part of the harbor when Mont Blanc blew up in what locals call The Narrows. Fortunately, Mont Blanc was not near any of the other explosives-laden vessels when it went up.
SS Curaca was loading horses for the war. She was thrown across the harbor. Of her 46-man crew, 45 humans (and the horses) perished. Old photo. Source.
At least 1,500 hundred lives were snuffed out in the blast and the following tsunami, and hundreds more died in the days ahead. Hundreds of remains were never identified. Some lasting results of the accident were standardization of fire hydrant and hose threads (responding fire departments found that the decimated Halifax department’s hydrants didn’t match their gear), more advance warning required for hazmat transits, and stricter maritime rules of the road in the harbor. There was a long series of saboteur hunts, enquiries, criminal trials, and private lawsuits, but in the end no one was singled out as solely to blame, or punished. It was a terrible accident, but in the end, just an accident.
There are several excellent sites on the blast.
The Technical Side
The manifest of the ill-starred Mont Blanc bares the spoor of the probable cause of the disaster — picric acid. This chemical was the first high explosive; its name comes from the Greek for “bitter.” Discovered and initially developed in the 18th Century, it became a dominant explosive and shell filling in the late 19th, when it was discovered initially by British scientist Sprengel. Picric acid was more powerful than the explosive that would come to replace it in most nations’ armories, TNT. The Japanese developed a picric acid derivative called Shimose, which they credited, in part, for their victories over Russia in naval and siege warfare; an American version was called Dunnite. Other terms for picric acid variants were Mélinite and Lyddite (these were the WWI French and British versions respectively). The Times wrote on 9 September 1898 of the British Army’s first use of Lyddite shells, in the Siege of Omdurman on 2 September:
Through Reuters Agency, Khartoum, September 5.
The breaching power of the Lyddite shells fired from the howitzers at the citadel of Omdurman prove to be enormous. The wall was a solid stone structure, 10 feet high by 4 feet thick, built of material brought from dismantled Khartoum. The accuracy of the howitzer fire is tested by the absolute havoc which was made of the Mahdi’s tomb at great ranges. (Nearly 2 miles).
This was a substantial improvement over the performance of the artillery of previous wars, but it came at the price of handling, storing, and stockpiling shells laden with this first (and fearfully unstable) high explosive.
Because unlike fairly stable TNT, picric acid and its salts — which form spontaneously on contact with common bases — are highly unstable; they tend to detonate when exposed to shock, friction, or flame. Picric acid corrodes metals and becomes more unstable in their presence, making it impossible to contain in metal cans or drums, and requiring special procedures for shell filling.
Before World War I, the German military had begun to shift to TNT. It was made by the same process that yields picric acid, just using a different feedstock; it’s only a little less explosive; and it’s vastly more stable. Over time all armies would follow suit, and fear of a repeat of the Halifax Explosion would be one reason (there were many other industrial and military accidents worldwide with picric acid that soured militaries on the chemical). Later, better HEs would be developed, both from the standpoint of stability and of energy, but it says something that TNT, which the Germans first put into shells in 1902, still is practically useful today.
The reason for going backwards in the power of explosive fillings was safety, and the far more stable TNT would have been unlikely to yield the Halifax Explosion. Even today, found Lyddite or Mélinite shells from WWI pose a threat. Even lab picric acid that dries out (of which more in a minute) requires an EOD call-out (small quantities of the acid are useful in biology).
Compounding the problem was that the material shipped in Mont Blanc was only partially shipped as wet picric acid, in which immersion in water reduces the material’s reactivity. Thousands of pounds were ultra-sensitive dry picric acid (the ship also contained large quantities of shock-sensitive guncotton).
Knowing the properties of their cargo, the actions of the crew of Mont Blanc — taking to the lifeboats, trying to warn everyone away from their burning ship — make a lot of sense. The actions of America, British and French ordnance in persisting in the use of this unstable chemical when stable alternatives were readily available are more puzzling to someone looking back at the destruction of Halifax by an a-bomb sized blast, from a vantage point a century ahead.