The Rules for Explosives in Ports

The houses on Kaye Street stood finished by the autumn of 1920, their clapboards painted in the muted greens and greys that the Relief Commission specified, their lots measured to the surveyor’s chain. The street had been rebuilt, but according to a plan that sorted its people; this new spatial order now demands a final look back at the harbour to see if its rules were similarly rearranged. In that same year, while carpenters drove the last nails into Richmond’s new construction, the Admiralty issued a circular that ran to seven pages of close type.

It prescribed, for the first time, a mandatory harbour pilot for any vessel carrying high explosives, designated anchorages outside the Narrows, restricted transit times, and a signalling protocol that required the master to declare his cargo before entering the channel. The document bore no mention of December 6, 1917. It did not need to. Every clause answered a specific failure.

The Mont-Blanc’s pilot Francis Mackey had not been required. Her anchorage had been inside the basin, close to the improvised pier where coal barges tied up. Her cargo was known only to her master and the naval authorities who cleared her. Her transit began at 7:30 a.m., when the harbour filled with outgoing traffic. The 1920 circular addressed each of these conditions with mechanical precision, as if the disaster had been a demonstration of flaws rather than an irruption of chaos.

Back in November 1917, the instructions given to Aimé Le Medec had occupied half a page. The French shipping company provided a routing order: New York to Halifax, Halifax to Bordeaux, join convoy at Bedford Basin. Naval authorities at Sydney, Nova Scotia, added a note about the gathering of the slow convoy. Nothing in the document addressed handling the vessel inside the harbour, the choice of pilot, the timing of transit, or signals to exchange with other traffic. SS Mont-Blanc was a cargo steamship that was built in Middlesbrough, England, in 1899 for a French shipping company. On Thursday morning, December 6, 1917, she entered Halifax Harbour in Nova Scotia, Canada, laden with a full cargo of highly volatile explosives. The gap between that sparse instruction and the 1920 circular measured the regulatory distance the disaster had forced.

The new rules did not emerge immediately. For more than two years after the explosion, the harbour continued under wartime arrangements that had proved, in the inquiry’s phrase, adequate for the movement of merchant shipping. The Wreck Commissioner’s report of February 4, 1918, blamed Mackey and Le Medec. The Supreme Court of Canada’s judgment of May 19, 1919, divided fault equally between Mont-Blanc and Imo. Neither court addressed the structural conditions: the split channel, the competing authorities, the convoy pressure that made speed a military virtue and caution a local inconvenience. The Privy Council’s final judgment of March 22, 1920, confirmed the equal division of blame. By then, the war had ended. The naval command that directed Halifax traffic dissolved. The harbour master’s office, which kept the logs and assigned the pilots, remained. This surviving institution received the new instructions and translated them into practice.

The 1920 circular arrived in Halifax in April, carried by a naval courier who delivered copies to the harbour master, the senior naval officer, and the commanding officer of the army garrison. The document’s preamble noted that recent experience had demonstrated the need for more precise arrangements in handling explosive cargoes. The first operational paragraph required that any vessel carrying high explosives—defined by a list that included TNT, picric acid, guncotton, and nitroglycerine—must take a harbour pilot before passing Chebucto Head. The pilot was to remain aboard until the vessel reached her anchorage or cleared the harbour entirely. This clause answered Mackey’s anomalous position: he had been a pilot, but not a harbour pilot, licensed for the St. Lawrence River and borrowed for this single voyage. The new rule made the harbour pilot mandatory, and made his presence continuous.

The second paragraph designated anchorages. Vessels carrying explosives were no longer to enter Bedford Basin unless the convoy assembled for immediate departure. Instead, they anchored in the lower harbour, in a zone marked on the attached chart by a red circle east of George’s Island. This anchorage placed them outside the Narrows, away from the pierhead traffic, visible to the signal station at Fort George. The Mont-Blanc had anchored inside the basin on the night of December 5, 1917, close to where the Imo would be loading the next morning. The new anchorage removed such vessels from the ordinary commerce of the port.

The third paragraph restricted transit times. Explosives carriers could move through the Narrows only between 6:00 a.m. And 8:00 a.m., or between 6:00 p.m. And 8:00 p.m. These windows avoided the mid-morning congestion of outgoing convoys and the mid-afternoon arrival of incoming traffic. The Mont-Blanc had entered the Narrows at 7:30 a.m., within the morning window, but she encountered the Imo at 8:45 a.m., when outgoing traffic peaked. The new rule compressed permitted transit into two hours at either end of the day, reducing the chance of meeting.

The fourth paragraph addressed signalling. The master of an explosives carrier was required to fly a red flag by day and show a red light by night. More significantly, he was to signal his cargo to the harbour master’s office before entering the channel, using a code that identified the type and quantity of explosives. This information was to be entered in a register kept at the signal station, available to pilots and harbour craft. The Mont-Blanc’s cargo was known to the naval authorities who cleared her from New York, but not to the harbour master’s office that directed her movements, and not to the master of the Imo, who saw only a tramp steamer with a French ensign.

These four paragraphs—pilot, anchorage, time, signal—formed a mechanism. Each requirement closed a gap that the explosion had exposed. The mechanism was not perfect. The 1920 circular said nothing about the speed of vessels in the Narrows, though excessive speed had contributed to the collision. It said nothing about the authority of the harbour master over naval vessels, though the Imo had been under naval charter. It said nothing about the training of pilots in handling explosive cargoes, though Mackey had never before guided a vessel so laden. But the mechanism addressed the most tractable failures: the lack of information, the diffusion of authority, the congestion of the channel.

Implementation of the new rules fell to the harbour master and his staff. The office occupied the same building on the waterfront, the same rooms where clerks had recorded the Mont-Blanc’s arrival on December 5, 1917. The senior clerk who had entered that arrival was still employed; he had testified at the Wreck Commissioner’s inquiry, identifying his own handwriting in the log. In 1920, he received the new register for explosives cargoes and began the work of translation. Each vessel that flew the red flag required a pilot assignment, a berth in the designated anchorage, a transit time within the permitted windows. The clerk’s work multiplied. Before the explosion, explosives carriers had been handled as ordinary merchant vessels, their hazards noted in confidential naval memoranda rather than in the harbour master’s open records. The new system made the hazards visible and the handling systematic.

The pilots experienced the change directly. Before 1917, a harbour pilot had guided vessels through the Narrows and into Bedford Basin, then left them to the basin pilots who moved them to their berths. The new rule required him to remain aboard until anchorage, extending his responsibility and his risk.

The pilotage fees were adjusted in 1921, doubling the rate for explosives carriers to compensate for the extended service. The pilots’ association, which had defended Mackey during the inquiry, now negotiated these terms with the harbour master.

The association’s minutes recorded the discussion: the special hazards of the explosive cargo justified the special remuneration, but also required the special training that the association proposed to provide. In 1922, the first course was offered, conducted by a retired naval officer who had served at Halifax during the war. The curriculum included the chemistry of the listed explosives, the behaviour of fire aboard a laden vessel, and the evacuation procedures that the Mont-Blanc’s crew had followed.

The convoy commanders experienced the change as delay. The 1920 circular required that explosives carriers join convoys only at the last moment, after the other vessels had assembled in Bedford Basin. This arrangement protected the assembled merchantmen from the risk of a single explosion, but it also complicated the sailing schedule. The convoy commander, who had previously directed traffic from the naval signal station, now received his instructions from the harbour master, who controlled the timing of the explosives carrier’s transit. The naval authorities protested this subordination. In 1921, a memorandum from the Admiralty to the harbour master’s office sought clarification: did the new rules apply to naval vessels under charter, as the Imo had been? The harbour master’s reply, preserved in the file, was categorical. All vessels carrying explosives, without exception, were subject to the circular of April 1920. The Imo’s status in 1917, ambiguous between naval and merchant, would not be repeated.

The masters of explosives carriers experienced the change as scrutiny. The new signalling requirement meant that their cargo was known, quantified, and recorded before they entered the channel. The register kept at the signal station showed, for each vessel, the type of explosive, the number of containers, the net weight, the shipper, and the consignee. This information was transmitted to the harbour master’s office, to the pilot, and to the fire station at the dockyard.

The master of a French munitions ship arriving in 1922 reported that his vessel was more closely examined at Halifax than at any other port of call. The examination included not only the documentation but the physical condition of the cargo: the barrels of picric acid were inspected for leakage, the benzol drums for proper stowage, the guncotton cases for the government seals that certified their manufacture. The Mont-Blanc’s cargo had been loaded in New York under the supervision of a French naval officer, but no Halifax authority had inspected it before the vessel entered the Narrows.

The city experienced the change as absence. The designated anchorage east of George’s Island was visible from the waterfront, but at a distance that reduced the familiar presence of dangerous cargo. Before 1917, vessels like the Mont-Blanc had tied up at the commercial piers or anchored in Bedford Basin, close to the settled districts of Richmond and Dartmouth. The new anchorage removed them from the ordinary life of the port. Children no longer watched the loading of explosives from the wharf; clerks no longer walked past barrels marked with the hazard diamond on their way to work. The red flag and the red light announced the vessel’s nature from a distance, warning rather than inviting attention.

This spatial rearrangement addressed what the disaster had revealed about time and visibility. The twenty minutes between the collision and the explosion had drawn a crowd to the waterfront, spectators who became casualties when the blast arrived. The new rules sought to prevent such intervals from opening, and to ensure that if they did, the spectators would not gather. The restricted transit times reduced the chance of collision; the mandatory pilot reduced the chance of navigational error; the designated anchorage removed the burning vessel from the pierhead; the signalling requirement allowed the authorities to clear the waterfront if fire broke out. The mechanism assumed that accidents would happen, and designed the response in advance.

The 1920 circular was not the final word. In 1923, the Admiralty issued a supplement that added nitrocellulose to the list of regulated explosives, responding to a fire aboard a British vessel at Liverpool. In 1925, the International Maritime Conference at Washington adopted conventions on the carriage of dangerous goods that drew on the Halifax experience. The harbour master’s office at Halifax participated in these developments, submitting its registers and its incident reports to the conference secretariat. The records showed no explosions, no fires, no collisions involving explosives carriers in the five years since the new rules had taken effect. This absence was the measure of their success.

But the mechanism had costs. The extended pilotage service, the restricted transit times, the inspection and documentation, all added delay and expense to the movement of war materiel. The French shipping company that had chartered the Mont-Blanc reduced its Halifax calls in the early 1920s, routing explosives carriers through Saint John or Sydney instead. The convoy commanders complained that the new rules complicated their schedules without improving security, since the explosives were still carried, still assembled into convoys, still exposed to submarine attack on the Atlantic passage. The harbour master’s office defended the system, citing the absence of incidents, but the defense acknowledged the tension: safety and speed remained opposed values, and the 1920 circular had chosen safety.

The regulatory turn of 1920 did not occur in isolation. It emerged from a sequence of administrative reviews that began while the fires of December 6 still smouldered.

Within forty-eight hours of the explosion, the Dominion government had appointed Colonel G.H. Desbarats to conduct a preliminary investigation, not into liability but into the harbour’s arrangements for dangerous cargo. Desbarats, who had served as deputy minister of militia and defense, possessed no maritime expertise, but he understood institutional failure.

His confidential report of December 15, 1917, identified what the later legal proceedings would obscure: the absence of any single authority responsible for the movement of explosives through the port. Naval authorities cleared vessels for convoy assembly; the harbour master directed pilotage and anchorage; the municipal police maintained the waterfront; no institution coordinated these functions. Desbarats recommended, among other measures, that the harbour master receive explicit authority over all vessels carrying explosives, regardless of their naval or commercial status. This recommendation, filed with the minister of marine and fisheries, provided the administrative foundation for the 1920 circular.

The Wreck Commissioner’s inquiry, which opened in January 1918, gathered evidence that supported Desbarats’s analysis without adopting his conclusions. Commissioner L.A. Demers, a judge of the Exchequer Court, focused his questions on the conduct of the two vessels’ masters and pilots. Yet the testimony repeatedly returned to structural matters. Harbour master F.W. Wyatt described the division of pilotage responsibilities between the Narrows and the basin, a division that had placed Mackey aboard the Mont-Blanc without authority over her final anchorage. Naval officers explained the convoy system, the pressure to assemble vessels quickly, the classification of ships by speed that had made the Mont-Blanc’s explosive cargo secondary to her slow engines. The transcript of the inquiry, published in February 1918, ran to 284 pages; fewer than thirty addressed the harbour’s regulatory framework, but those pages contained the raw material for reform.

The Supreme Court of Canada’s proceedings, which occupied six days in May 1919, produced a different kind of record. The court’s mandate was to apportion damages, not to recommend prevention. Yet the arguments presented by counsel for the various parties—French government, Belgian Relief Commission, Norwegian owners of the Imo, Canadian underwriters—exposed the same gaps that Desbarats had identified. Each party sought to demonstrate that the other’s institutional arrangements had contributed to the disaster. The French government emphasized the naval clearance procedures that had directed the Mont-Blanc to Halifax without informing local authorities of her cargo. The Belgian Relief Commission stressed the harbour master’s failure to regulate traffic in the Narrows. The court’s equal division of blame, announced on May 19, 1919, satisfied no party completely, but it validated the perception that responsibility had been too diffuse to assign definitively.

Between the Supreme Court judgment and the 1920 circular, a final administrative review occurred within the Admiralty itself. The director of transports, responsible for the movement of munitions across the Atlantic, commissioned a study of explosive cargo handling at all North Atlantic ports. The resulting memorandum, dated January 1920, compared Halifax with New York, Liverpool, and Brest. Halifax alone, the memorandum noted, permitted explosives carriers to anchor within the commercial basin, to transit without mandatory pilotage, and to enter the harbour without declaring cargo to civil authorities. The comparison was invidious but accurate. The Admiralty’s transport department recommended standardization on the New York model: designated anchorages outside population centers, compulsory pilotage, advance notification of cargo. The 1920 circular, issued in April, implemented these recommendations with the specific adaptations that Halifax’s geography required.

The translation of policy into practice required negotiation with local interests. The Halifax pilotage association, which had defended Mackey and now faced expanded responsibilities, sought guarantees of support.

This choice was institutionalized. The Halifax harbour that emerged from the reconstruction was not the wartime harbour of 1917. The naval command that had directed convoy traffic had dissolved; the army garrison that had provided emergency relief had been reduced; the Relief Commission that had rebuilt Richmond would close in 1926. The harbour master’s office survived, with its registers, its pilots, its rules for explosives. The 1920 circular became the foundation of a permanent regulatory regime, copied by other ports, revised by later conventions, but recognizably the same mechanism that had been forged in the aftermath of the explosion.

The new rules were in place. A French munitions ship entering Halifax in 1922 followed a channel marked by buoys, guided by a pilot who stayed aboard until anchorage, flying a red flag that announced her cargo to the signal station before she passed Chebucto Head. She anchored east of George’s Island, visible from the waterfront but distant from it, and waited for the convoy to assemble in the basin beyond. The clerk in the harbour master’s office entered her particulars in the register: TNT, picric acid, benzol, guncotton, the quantities and the shipper’s name. The pilot’s fee was doubled. The transit time was checked against the permitted window. The mechanism operated, visible and checkable, a concrete consequence of the disaster that had made such visibility necessary.