Fort McNab
As naval weaponry increased in range and destructive potential towards the end of the 19th century, it became necessary to push Halifax Harbour defences further to seaward. This was in order to be able to engage equally increasingly powerful enemy shipping before it could get close enough to bombard the naval dockyard, city and harbour. Thus, two new gun batteries with long range breech-loading guns of greater accuracy were constructed: Sandwich Battery south of York Redoubt, and Fort McNab on McNab’s Island.
Begun in 1888, Fort McNab was completed in 1892. It was located on a 113-foot (34 metre) hill, the highest ground in the southern part of McNab’s Island; this was nearly 3 miles (over 4 km) from the southernmost tip of the Halifax peninsula, at the time the farthest to seaward of the port’s defences. With its newly-introduced long-range breech-loading guns, it was designed to command the offshore approaches from Chebucto Head and the Sambro Ledges in the west, to Cole Harbour and Lawrencetown in the east, and with its secondary armament to cover the shoreline between Chebucto Head and York Redoubt.
Fort McNab was constructed largely of concrete within earthen ramparts. It was the first gun emplacement of the Halifax Fortress to be built primarily of concrete and the first to mount breech-loading guns. Its design featured new Coastal Defence fortification concepts for that time: flat, sloping land surrounded the emplacements to deflect and absorb enemy projectiles; its contours were similar to the surrounding ground for concealment; and its armament was distributed over a broad front in open concrete emplacements.
The fort’s original main armament, mounted in December 1890 consisted of a single 10-inch 32-ton Mk I breech loader (BL), a gun which was used for coastal defence throughout the British Empire and in British battleships from 1885 until after the First World War. It could fire a 500-pound (227 kg) projectile 10,000 yards (9 km) – its maximum range. The battery was equipped with a Depression Range Finder (DRF) and an E Mk II Depression Position Finder (DPF) in a Command Post just behind the battery, in addition to separate Position Finding (PF) cells located nearby.
The 10-inch BL gun was made obsolete by the addition of a newer 9.2-inch 28-ton BL Mk X gun with improved ballistic properties, on a Mk V mounting in 1904. The 9.2-inch BL, even though of smaller caliber, was capable of launching a 380-pound shell 17,600 yards (16 km). This gave it a significant range improvement over the 10-inch BL, as well as having a rate of fire 2½ times faster. A second 9.2-inch BL was planned to be installed at Fort McNab but it never materialized. The 10-inch BL was eventually dismounted in 1911 and buried southeast of the fort in 1913. It was dug up in recent years and since 2010 has been on display at Fort McNab – the largest gun ever mounted in the Halifax Fortress. It is believed to be one of only three that have been preserved worldwide and the only one to be still mounted in its original location.
Secondary armament was initially two 6-inch 7-ton Mk IV breech loaders, which were replaced by two 6-inch BL Mk VII guns in 1903/04. Equipped with the Mk III No. 12 Depression Range Finder, the 6-inch battery boasted an effective range of 6,000 yards (5½ km) which allowed it to reach as far as Herring Cove and Devil’s Island.
All guns were designed to fire en-barbette, over the parapet. Each gun position had a nearby crew shelter and a bomb-proof magazine buried deep underground containing a mixture of armour-piercing, high explosive and shrapnel shells. Various brick and wooden buildings housing barracks, stores, offices and other support facilities were clustered to the west of the gun batteries. One of the most prominent features was the row of seven casemates set into the hillside just behind the guns, used for various storage and support equipment purposes. The fort was surrounded by a 10-foot-tall iron picket fence in a ditch. Within the footprint of the fort is a small enclosure which contains the private burial ground of the McNab family, the island having been originally purchased by Peter McNab in 1782 and the family connection enduring until the 1930s.
Manning for Fort McNab in the 1890s would have been 72 to 93 artillerymen, 4 infantry machine gunners, and up to 11 engineers. The fort was taken over by the Canadian Army in 1905 on the departure of the British from Halifax, and thence manned by No. 1 Company, Royal Canadian Garrison Artillery. Fire from Fort McNab and Sandwich Battery was coordinated by the Fortress Fire Command Post near York Redoubt, with a Battery Command Post (BCP) being added at Fort McNab, on the elevation behind the 6-inch battery.
The fort was mobilized on 30 July 1914 for the First World War (1914-18), during which Fort McNab functioned also as marine traffic control examination station, with the 6-inch battery initially serving that purpose. Two searchlights (Numbers 11 and 12) and an associated power generating station were placed near the shore about 500 yards SSE of Fort McNab in August 1914 and a 6-pdr (2.244-inch) quick-fire (QF) Hotchkiss Mk II gun was installed on the parapet between the 6-inch guns in 1916, to support the examination service
As an indication of its prominence in the defences of Halifax, Fort McNab was inspected by high-ranking officials regularly before, during and after the First World War:
- by MGen Sir Percy N. Lake (Inspector General of the Canadian Militia) in October 1908;
- by HRH The Duke of Connaught (Governor General of Canada) in August 1914, June 1915 and August 1916;
- by the 9th Duke of Devonshire (Governor General of Canada) in 1917;
- by Prince Arthur of Connaught in August 1918;
- by Admiral of the Fleet Viscount Jellicoe in December 1919; and
- by General Sir Arthur Currie (Inspector General of the Canadian Militia) in May 1920.
Although effectively mothballed from 1932, the 9.2-inch BL gun remained in operation until 1941 when it was relocated to the new Devil’s Battery at Hartlen Point.
During the Second World War (1939-45), Fort McNab served three roles: as a counter bombardment battery (using the 6-inch guns and, until 1941 the 9.2-inch gun) for defence of the harbour approaches; to control the two new searchlight emplacements installed at the south end of island in 1941; and to control the shipping examination anchorage, gaining it the moniker “Gatekeeper of Halifax Harbour.” Throughout it was manned by the 52nd Heavy Battery, 1st (Halifax) Coast Brigade, Royal Canadian Artillery.
The Second World War also saw a new Battery Command Post built, in 1940-41 beside the older one; the 6-pdr examination service gun replaced by a heavier 75mm gun in 1943, and in the final months of the war a radar post constructed over the now vacant 9.2-inch gun emplacement on the left flank – effectively a Radar Battery Observation Post (BOP). The newly-developed 3,000 MHz (S-band) CDX (Coastal Defence Fire Control) radar was fitted here, capable of detecting large vessels at a maximum range of 23 miles (38 km) and able to spot shell splashes out to 13 miles (21 km); it was therefore useful as both a search radar for locating and tracking enemy shipping and as a fire control radar for correcting the fall of shot from shore batteries onto the target. It also made the battery effective at night and in fog, when its target was not visible to the eye. The CDX radar at Fort McNab was one of three such radars installed around that time for the Halifax Fortress, the other two being at Duncan’s Cove near Chebucto Head Battery and at Devil’s Battery on Hartlen Point. The radar tower consisted of an equipment room and operators’ consoles on the lower level and an observation room on the second level featuring a new No. 17 Director for visual backup to the radar, which sat on the roof.
During the 1950s, Fort McNab was part of Canada's Cold War coastal defence strategy. In 1953 one of the 6-inch BL guns was replaced by a 4-inch twin naval gun. In 1954 the three 9.2-inch BL guns from Devil’s Battery, including the one that had previously been at Fort McNab, were given to Turkey as NATO mutual aid; there they were used to guard the Bosphorus Strait until about the late 1990’s. The fort was finally closed and dismantled in 1960. Fort McNab was transferred from the Defence Department to the National Parks Branch in 1963, and in 1965 declared a National Historic Site. Various remaining buildings on the site, including the 1940 BCP, the radar tower, casemates, crew shelters and others were designated as Recognized Federal Heritage Buildings in 1997. Fort McNab is today administered by Parks Canada.
Fort McNab illustrates the evolution of Coastal Defence technology from the 1880s to the 1940s. Significant advances in ordnance, detection and fire control are all represented at the site. Among its more important extant resources are:
- the largest (10-inch) breech loading emplacement in the Halifax Fortress;
- early position finding cells (more generally called range finding cells);
- an extensive magazine complex;
- searchlight defences; and
- a radar post.
References:
Doug Knight The 9.2 Coast Defence Gun in Canadian Service. Ottawa 2020.
Harry Piers The Evolution of the Halifax Fortress, 1749-1928. NS Public Archives 1947.
A.J.B. Johnston Defending Halifax: Ordnance, 1825-1905. Parks Canada 1981.
Dag Schmidtke The British 9-2-inch Breech Loading Coast Defence Gun
The Friends of McNab’s Island Society website (https://mcnabsisland.ca)
LAC RG24 Vol 24111 Fort McNab Record Book. Library and Archives Canada.
Parks Canada Directory of Federal Heritage Designations (https://www.pc.gc.ca/apps/dfhd)