Looking north from a grain elevator towards Acadia Sugar Refinery, circa 1900, showing the area later devastated by the 1917 explosion
Dartmouth lies on the east shore of
Halifax Harbour, and
Halifax is on the west shore. Halifax and Dartmouth had thrived during times of war; the harbour was one of the British
Royal Navy's most important bases in North America, a centre for wartime trade, and a home to
privateers who harried the British Empire's enemies during the
American Revolution, the
Napoleonic Wars, and the
War of 1812.
The completion of the
Intercolonial Railway and its Deep Water Terminal in 1880 allowed for increased steamship trade and led to accelerated development of the port area, but Halifax faced an economic downturn in the 1890s as local factories lost ground to competitors in central Canada.
 The British garrison left the city in late 1905 and early 1906. The Canadian Government took over the
Halifax Dockyard (now
CFB Halifax) from the Royal Navy.
 This dockyard later became the command centre of the
Royal Canadian Navy upon its founding in 1910.
Just before the
First World War, the Canadian government began a determined, costly effort to develop the harbour and waterfront facilities. The outbreak of the war brought Halifax back to prominence. As the Royal Canadian Navy had virtually no seaworthy ships of its own, the Royal Navy assumed responsibility for maintaining Atlantic trade routes by re-adopting Halifax as its North American base of operations. In 1915, management of the harbour fell under the control of the Royal Canadian Navy under the supervision of Captain Superintendent Edward Harrington Martin; by 1917 there was a growing naval fleet in Halifax, including patrol ships, tugboats, and minesweepers.
The population of Halifax/Dartmouth had increased to between 60,000 and 65,000 people by 1917.
 Convoys carried men, animals, and supplies to the European theatre of war. The two main points of departure were in Nova Scotia at
Cape Breton Island, and Halifax.
Hospital ships brought the wounded to the city, and a new military hospital was constructed in the city.
The success of German
U-boat attacks on ships crossing the
Atlantic Ocean led the
Allies to institute a
convoy system to reduce losses while transporting goods and soldiers to Europe.
Merchant ships gathered at
Bedford Basin on the northwestern end of the harbour, which was protected by two sets of
anti-submarine nets and guarded by patrol ships of the Royal Canadian Navy.
The convoys departed under the protection of British
destroyers. A large army
garrison protected the city with forts,
gun batteries, and anti-submarine nets. These factors drove a major military, industrial and residential expansion of the city, and the weight of goods passing through the harbour increased nearly ninefold. All
neutral ships, bound for ports in North America, were required to report to Halifax for inspection.