Artillery in Canada: 10-inch Mortar round, 17th century, Fort Nashwaaksis, York Sunbury Historical Society, Fredericton Region Museum, Artefact

FRM Artefact, c17^th century 10-inch Mortar round

(Author Photo)

          A heavily corroded British cast iron 10-inch mortar round found on the site of Fort St. Joseph may be one of the earliest military artifacts in the collection of the Fredericton Region Museum.  The French Fort once stood on the north side of the Nashwaak River across from the present-day Fort Nashwaak Hotel.  The artefact was donated to the museum by LeBaron Bell and recorded in the records on 11 April 1932.

          This mortar round would have been fired from a smoothbore muzzleloading (SBML) Mortar, with a weight greater than 2,000 lbs.  It was discovered on the site of the British siege of Fort St. Joseph that took place on the banks of the Nashwaak River on the Northeast corner of present-day Fredericton, in 1696.

          In the late 1600s, these mortars were in wide-spread use by France and England, and at that time were called “grenades”. English mortar rounds in the late 17^th century ranged in size from 6 to 18 inches, with references to these calibres appearing regularly in the various inventories by the Office of Ordnance in London from 1675 onwards.  A damaged 18-inch cast iron specimen likely cast in England in 1684 is recorded in the collection of the Tower Armouries in London.[1]

In 1696, the capital of Acadia was Fort Nashwaak (Fort St. Joseph), on the East side of the St. John River, now part of the city of Fredericton. Robineau de Villebon was the Commandant in charge of a fort 200 feet square with four bastions and surrounded by a palisade and ditch.[2]  A New England force led by Colonel John Hawthorne prepared to attack the fort on 18 October.  

Villebon had placed lookouts at the river’s mouth and knew what was coming. He onlyh had about 100 soldiers to stand against Hathorne’s 500, but his defences at the fort were hastily improved. In preparation for the British attack, de Villebon built a second palisade around the fort and mounted ten cannon and eight swivel guns on its walls.  He had also sent out word calling up every available Acadian for service. A message was also sent to Father Simon at Meductic, who had the Maliseet First Nations warriors go to the fort to aid in the coming fight with Hawthorne.

It was mid-October when word arrived that Hathorne was only a few miles below Jemseg. The British set up a camp and manned an artillery battery across the Nashwaak River, which likely included the mortar that would have been used to fired the round now with the museum.  Villebon addressed his men and cries of ”Vive le Roi” echoed through the fort. The first attack occurred the next morning, and Villebon kept his men within the fort rather than having them cross the Nashwaak River under fire from the British forces. This attack was repulsed by cannon fire.[3]

Cannon and musket fire then exchanged btween the two opposing forces, but Villebon’s guns were better mounted and more effective. The British were unable to make progress that day and because of the cold, they lit fires at night to keep warm.  The fires attracted a further barrage from the fort and the British soldiers had to extinguish their fires.  Hawthorne’s forces came under more of de Villebon’s cannon fire from the fort again in the morning. After two days of ineffective bombardment and suffering the harassment of French and First Nation's skirmishers in the woods, the British withdrew on 20 Oct 1696.[4]  They sailed down river, ending the battle of the Nashwaak.

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Fort Nashwaak, built by Commandant de Villebon in 1691-92. From Clarence Webster, Acadia at the End of the 17^th Century

In broad terms, a mortar is a piece of artillery designed for indirect fire at very high angles to aim at targets protected by walls, trenches or rough terrain. That is in contrast to regular cannon which are designed mostly for direct fire, with their projectile being propelled straight at their target rather than in a high arcing curve.

Mortars are first recorded in military history in the early to mid-15th century in both Korea and the siege of Constantinople and retained the same basic shape up until the Great War. The weapons gain their name because they are similar to an apothecary’s thick-walled bowl.

Mortars of that time had a few main characteristics. The first one was its projectile, its shell or bomb, a very large projectile filled with black powder. It had a cast iron body with handles/ears for loading and thicker walls at the bottom to resist the initial propelling blast (Fig.4), said blast also being used to light the time fuse(C.) made up of a hollow wooden cone filled with either compressed black powder or slow-burning paper.

Mortar Diagram. (The Napolean Series Archive)

Although less propellant was used proportionally to the weight of the projectile compared to regular cannon -the latter needing large amounts to shoot with a flat trajectory- each shot still required several kilos of black powder to move these massive projectiles, resulting in incredible pressure building up inside the gun. To manage this, mortar barrels are built with extremely thick walls, especially around the propellant chamber on top of which the bomb sits.

The final characteristic of a mortar is its very sturdy baseplate, made first from wood then from cast iron starting in the 19th century, made to absorb the recoil of the gun without being crushed against the ground. It also included a wedge and its resting block -the coin demire and coussinet in French, which allowed the gunner to fine-tune the firing angle of the gun, which along with the amount of propellant was used to range it. Most mortars fired between a 45° and 60°angle.

(Author Photo)

French Cast Iron 13-inch Mortar, with the letter C and the number 4338 inscribed on the barrel, (Serial No. 22) on the right trunnion, 1, 30-48-cm bore, ca.1758, from the Fortress of Louisbourg, Nova Scotia.  On display in the Canadian War Museum, Ottawa.

These very large mortars were almost exclusively used when attacking or defending fortifications to destroy targets beyond its walls. Beginning in the 17th century lighter mortars were used that worked equally well in the field. The bronze Coehorn mortar, named after Dutch military engineer Menno van Coehoorn, was a light artillery piece that could be carried by two soldiers and used to fire upon entrenched soldiers or large formations. Although the smaller projectiles did not fragment as well as our modern projectiles, and their trajectory could be avoided by any soldier with a keen eye and a bit of luck, it proved very effective at its main purposes of providing cover, suppressive fire and laying waste to enemy trenches. While siege mortars mostly evolved into even larger howitzers around the second half of the 19th century, it is these smaller coehorns that evolved into modern mortars.[5]

[1] Brian G. Scott, The deployment of Mortars in Ireland up to the 1689 Siege of Londonderry, Ulster Journal of Archaeology, Vol 73, 2015-2016,

[2] Joseph Robineau de Villebon (22 August 1655 – 5 July 1700), was born in New France, but received much of his education and military experience in France. He returned to New France about 1681 and deployed to Acadia c1685, where he re-established French rule.  On 7 April 1691, the king appointed him “commandant in Acadia,” a position he held until his death at Fort Saint-Jean in Acadia. He built the capital at Fort Nashwaak and was able to maintain the New England-Acadia boundary in present-day Maine because of his military talents and his skill in dealing with the First Nation Wabanaki Confederacy. (Dictionary of Canadian Biography)

[3] John Wood, blog, The Razing of Chignecto and the Attack on Fort Nashwaak, 5 July 2017.

[4] W.E. (Garry) Campbell, The Road to Canada, The Grand Communications Route from Saint John to Québec, (Goose Lane Editions and the New Brunswick Military Heritage Project, Fredericton, New Brunswick, 2005), pp. 21-23.

[5] https://qsy-complains-a-lot.tumblr.com/post/614034303952748544/what-is-a-mortar/

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