Reasons for building the Towers and Batteries.
Since Theobald Wolfe Tone and the Society of United Irishmen attempted to rally France behind the Irish cause in the 1790s and with the coming to power of Napoleon Ireland was seen as the likely landing place for an invasion force. The Mouth of the Shannon was one of the three invasion areas ( the others were Galway and Bantry Bay) included in the French Directory’s instructions to Vice- Admiral Villaret de Loveuse in October 1796, during the preparations of an expedition to Ireland.This led to the British Admiralty constructing the a system of Signal Stations (51) as observation posts, together with 50 Martello towers, each maintaining a garrison of troops, officers and heavy artillery.
In addition to these a total of 10 quadrangular towers protecting batteries were built in Ireland between 1809 and 1817 on the coast in places that were particularly vulnerable to invasion. Seven were built to defend the River Shannon which was thought to be place the invasion was most likely to take place as it provided access to Limerick and the centre of Ireland. Six of these quadrangular towers were constructed along the shores of the Shannon Estuary below Limerick, Tarbert and Carrig Island on the south shore and Kilcredaun, Doonaha, Scattery Island and Kilkerrin on the north shore. The other one was built on the Upper Shannon to defend a ford at Keelogue below Athlone. Two others were built on the shores of Lough Swilly in County Donegal and one on Bere Island in Bantry Bay in County Cork.
Description of the Quadrangular Towers and Batteries.
Quadrangular towers were always to be found closing the gorge of a detached battery and were there to protect the battery from a landward side attack as well as cover for the battery of 24 pounder guns.
The batteries housed the gunners and the ordinary troopers. It was well defended by deep dry moats and was bombproof.All the 10 batteries formed a D-shaped enclosure in plan with masonry on the the scarp and counterscarp of the dry moat . Entrance to the batteries was across a drawbridge over the dry ditch or moat. The defensible guardhouses were entered from within the battery by a drawbridge slightly wider than the entrance doorway, over which the keystone bears the dates of construction. The guardhouses had basements or lower ground floors, level with the base of the dry moat in which it stands. The upper floor, level with the ground level of the battery, was approached by the drawbridge; above this floor level is the gun platform carried on the barrel-vaulted ceiling of the first-floor apartments.Musket-loops were provided at the lower levels, allowing for close defence of the moat in the manner of a caponnière. Musket-loops at the upper floor levels, were fitted with shutters on the outer face of the wall, commanded the interior of the battery. Other loops are arranged on the opposite side at this level, facing the approach to the rear of the battery on the landward side. On the roof-level gun platform, protected by broad parapets some six feet in height, were two guns mounted on traversing platforms: howitzers or carronades for defence of the landward side of the battery and they fired exploding projectiles. The traversing platforms, one at each end of the roof, enabled the guns to be trained through an angle of about 270 degrees, covering the ground on each flank of the battery and to the rear.
The main armament of the battery consisted of six 24-pounder guns mounted on traversing platforms, each revolving on a front pivot behind the inner face of the parapet.The range of the 24 pounder guns was 2km.Most of the guns could be simultaneously pointed at the same point. They fired either hot cannon shots to set fire to a vessel or cold shots to sink a vessel. The cannon shots were held in a bomb proof section within the barracks.
Scattery Quadrangular Tower and Battery
Situated on the southern extremity of the island, close to the later lighthouse, this battery is in reasonable condition and of the same layout as the other batteries.The Board of Works have now taken over looking after the heritage on Scattery Island and the battery has been recently cleared of overgrowth ,mainly briars and a great job was done by them. A feature that it shares with Corran Point on Carrig Island and Kilkerrin is the indented outline of the inner face of the curved parapet. This reduces the thickness of the parapet immediately in front of the pivot of each traversing platform. In 1811 Scattery was noted as having eight guns, perhaps in a temporary battery that preceded the present structure. The picture shows the D shape with the battery on the straight wall and the six cannons on the traversing platforms around the curved section. With the battery on Carrig Island just 2 miles away these two batteries were ideally placed to stop if needed any ship passing up the Shannon.