Canadian Consulting Engineer

The Dyslexic Forts

October 1, 2006
By Alistair Mackenzie

As part of our canadian forces' difficult and dangerous assignment in Afghanistan, several forward operating bases have been established as outposts in what was formerly Taliban territory. Earlier thi...

As part of our canadian forces’ difficult and dangerous assignment in Afghanistan, several forward operating bases have been established as outposts in what was formerly Taliban territory. Earlier this year, it was announced that one of these, north of Kandahar, was to be named Forward Operating Base “Martello.”

The use of the name Martello for a defensive military strongpoint will come as no surprise to anybody familiar with the history of military fortifications. In the early 19th century, the Martello tower was a popular type of coastal defensive structure. Well over 100 of these odd structures were built in several locations around the world. Sixteen were constructed in Canada, 11 of which survive to provide us with an important link to the early days of engineering in Canada.

The British employed the Martello designs in Ireland, the Channel Isles, Minorca, South Africa, the West Indies and the United States. Even Australia was not omitted, and a single tower, possibly the last Martello Tower to be constructed, was built in 1850 at Fort Denison in Sydney Harbour.

The name “Martello,” however, appears to have resulted from a misspelling or mispronunciation of the name of a fortification at Cape Mortella in Corsica that the British navy had found particularly difficult to capture. In early 1794, this stone tower had been attacked by two British warships, neither of which was able to make much impression on it.

The design of the Corsican tower appeared to the British to be so effective against attack by its warships that they copied the idea and proceeded to construct virtual replicas for their own coastal defensive purposes.

It seems they intended to name their forts after the location of the original tower. However, the British towers became “Martello” Towers instead of “Mortella” Towers, thanks to a dyslexic officer of the Royal Engineers who switched the letters “o” and “a” in his report on the original tower’s design.

With an invasion by Napoleon Bonaparte’s French army in the early 1800s a very real possibility, the British military first decided to use the fortification to protect England’s south coast from the threat. The man selected to develop the design of the Martello tower for this purpose and who would eventually construct 105 of them on the south coast of England between 1804 and 1812 was a general by the name of William Twiss.

William Twiss bridges military-civil engineering gap

William Twiss’ career is closely linked to Canada. Following service in America during the War of Independence, Twiss was posted to Canada and became the British military’s chief engineer in this country. In this capacity, he constructed a number of military facilities, but he was also one of Canada’s earliest engineers to bridge the gap between military and civil engineering. His great contribution to Canadian civil engineering was the construction of the Coteau du Lac Canal, on the shore of the St. Lawrence some 40 kilometres southwest of Montreal. This was the first locked canal in North America, and was commenced in 1779. Following its completion, Twiss returned to England in 1783 and most of his later career was spent in the construction of the Martello towers on the English coast.

Despite the fact that the principal design and construction engineer of Martello towers spent a considerable part of his career in Canada, ironically he was to have no part in building the Canadian Martello towers.

Sixteen in Canada

The Canadian Martello towers were also built as defences against possible ship-borne invasions. The first was built in Halifax in 1796 for defence against French attack. It cost approximately 2,400 pounds sterling to build and it survives today as the Prince of Wales Tower. Four other similar towers were then built around Halifax Harbour, none of which have survived. The Halifax structures were formidable adaptations of the Martello tower principle and much stronger than any of the succeeding Canadian towers.

Four towers in more “traditional” format were built on the Plains of Abraham in Quebec City, overlooking the St. Lawrence River, between 1808 and 1812, this time as defence against a possible invasion by the Americans. These Martello towers were constructed under the overall direction of engineer officer Ralph Henry de Bruyres, and were commenced under the direct supervision of another notable figure in early Canadian civil engineering history, Lt. Col. John By. At that time a junior officer, John By was later to become much better known as the engineer of the Rideau Canal in Ottawa. Three of the Quebec City towers survive.

A single tower, the Carleton Martello Tower, was built overlooking the harbour of Saint John, New Brunswick, and it too survives to the present day. Six towers were built at Kingston, on Lake Ontario. Two of these, currently being restored, were built into the walls of the branch ditches of Fort Henry and are slimmer and less massive than the typical towers. The other four, the Murney Tower on Murney Point, the Victoria or Shoal Tower located in the water in front of the Market Battery, the Fort Frederick Tower and the Cathcart or Cedar Island Tower were “full” Martello towers and are perhaps the most complex in design of all of the Canadian versions. Canada’s second prime minister, Alexander Mackenzie, who was a stone mason before he became a politician, worked on the construction of the Fort Frederick Tower at the Royal Military College.

A solid round structure built for a fight

Although there were several variations in design, the towers were essentially round defensive forts of masonry construction, usually between 12 to 15 metres high and 12 to 15 metres in diameter. There were normally two floors, both accessed by a single doorway at around 6 metres above ground level that gave directly onto the barrack floor on the second level. The ground floor housed storage space and the magazine. The Fort Frederick Tower is unique amongst Martello Towers in having three floors.

The towers had a flat roof used for mounting guns — frequently a number of the 32-pound “Carronades” then in general use. The circular masonry walls were in some cases up to 4.6 metres thick (as at Fort Frederick) on the “water” side from which an attack was to be expected, and perhaps 2 metres thinner on the safer, landward side. The solid walls, together with a stout central round brick pillar that supported the roof, were the most important design features. The resulting solid round structure was very resistant to artillery attack and its height provided a commanding field of fire.

Although the Martello towers did not have the strength of a more traditional military fort or redoubt, they became popular with the military because they were cheap to build and with their simple design could be constructed rapidly. One distinction in the design of the Canadian towers compared to their English counterparts was that in recognition of our climate the Canadian towers had “temporary” cone shaped roofs constructed over the main tower roof to protect both guns and soldiers from snow. These temporary wooden roofs were easily removed when the tower needed to be brought into action.

Their legacy

The Canadian Martello towers were built towards the end of the era when military engineers designed the major construction projects in Canada, and from about this time onwards it was the true “civil” engineers who gradually took over developing the country’s infrastructure.

We do not know how effective Martello towers would have been in resisting invasion as fortunately none was ever seriously tested in combat. Only one, in Ireland, was ever captured and this was apparently a very “low key” event that did not test the tower’s capabilities. Following the end of the War of 1812, most of the Canadian towers were gradually phased out of military use. Some, however, saw short-term service in a variety of functions as watch towers, prisons or military
storage facilities during both World Wars.

From a heritage point of view, we are fortunate that 11 of the original 16 of these unique structures have survived in Canada. Most are now national historic sites in the care of Parks Canada. Additionally, the Prince of Wales Tower in Halifax, the Carleton Martello Tower in Saint John, Martello Tower #1 on the Plains of Abraham, and the Murney Tower and Fort Frederick in Kingston now house excellent museums.

With their characteristic shape and their odd dyslexic name, these surviving towers are excellent examples of the historic types of structures that form Canada’s rich military and civil engineering heritage.

Alistair MacKenzie is a professor emeritus at Ryerson University in Toronto. He is also the immediate Past President of the Canadian Society for Civil Engineering.

If you enjoyed this article and would like to see previous articles on Canadian engineering history by the author, view the archives at, or contact the editor,


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