Martello towers, sometimes known simply as Martellos, are small defensive forts that were built across the British Empire during the 19th century, from the time of the French Revolutionary Wars onwards. Most were coastal forts.
They stand up to 40 feet (12 m) high (with two floors) and typically had a garrison of one officer and 15–25 men. Their round structure and thick walls of solid masonry made them resistant to cannon fire, while their height made them an ideal platform for a single heavy artillery piece, mounted on the flat roof and able to traverse, and hence fire over, a complete 360° circle. A few towers had moats or other batteries and works attached for extra defence.
Martello towers were inspired by a round fortress, part of a larger Genoese defence system, at Mortella (Myrtle) Point in Corsica. The designer was Giovan Giacomo Paleari Fratino (el Fratin), and the tower was completed in 1565.
Since the 15th century, the Corsicans had built similar towers at strategic points around the island to protect coastal villages and shipping from North African pirates. The towers stood one or two storeys high and measured 12–15 m (39–49 ft) in diameter, with a single doorway five metres off the ground that one could access only via a ladder which the occupants could remove.
Local villagers paid for the towers and watchmen, known as torregiani, who would signal the approach of unexpected ships by lighting a beacon fire on the tower’s roof. The fire would alert the local defence forces to the threat. Although the pirate threat subsequently dwindled, the Genovese built a newer generation of circular towers (the Genoese towers), that warded off later foreign invasions.
On 7 February 1794 as part of the siege of Saint-Florent, two British warships, HMS Fortitude (74 guns) and HMS Juno (32 guns), unsuccessfully attacked the tower at Mortella Point; the tower eventually fell to land-based forces under Sir John Moore after two days of heavy fighting. What helped the British was that the tower’s two 18-pounder guns fired seaward, while only the one 6-pounder could fire land-ward.
Vice-Admiral Lord Hood reported:
…The Fortitude and Juno were ordered against it, without making the least impression by a continued cannonade of two hours and a half; and the former ship being very much damaged by red-hot shot, both hauled off. The walls of the Tower were of a prodigious thickness, and the parapet, where there were two eighteen-pounders, was lined with bass junk,[Note 1] five feet from the walls, and filled up with sand; and although it was cannonaded from the Height for two days, within 150 yards, and appeared in a very shattered state, the enemy still held out; but a few hot shot setting fire to the bass, made them call for quarter. The number of men in the Tower were 33; only two were wounded, and those mortally.
Late in the previous year, the tower’s French defenders had abandoned it after HMS Lowestoffe (32 guns) had fired two broadsides at it. The British removed the guns to arm a small vessel; consequently, the French were easily able to dislodge the garrison of Corsican patriots that had replaced them. Still, the British were impressed by the effectiveness of the tower when properly supplied and defended, and copied the design. But, they got the name wrong, misspelling “Mortella” as “Martello” (which means “hammer” in Italian). When the British withdrew from Corsica in 1803, with great difficulty they blew up the tower, leaving it in an unusable state.
The towers were about 40 feet (12 m) high with walls about 8 feet (2.4 m) thick. In some towers the rooms were not built in the center, but more to the landside, leaving the walls thicker on seaside. These were cases where an attack with a cannon from the landside was thought very unlikely. Entry was by ladder to a door about 10 feet (3.0 m) from the base above which was a machicolated (slotted) platform which allowed for downward fire on attackers. The flat roof or terreplein had a high parapet and a raised platform in the centre with a pivot (sometimes a converted cannon) for a cannon that would traverse a 360° arc. (Some towers were designed to carry more than one gun, with each having a more limited arc of fire.) The walls had narrow slits for defensive musket fire.
The interior of a classic British Martello tower consisted of two storeys (sometimes with an additional basement). The ground floor served as the magazine and storerooms, where ammunition, water, stores and provisions were kept. The garrison of 24 men and one officer lived in a casemate on the first floor, which was divided into several rooms and had fireplaces built into the walls for cooking and heating. The officer and men lived in separate rooms of almost equal size.
A well or cistern within the fort supplied the garrison with water. An internal drainage system linked to the roof enabled rainwater to refill the cistern.