The history of the largest military structure in Ireland…
The first fortification on Spike Island arrived in 1779 while the American War of Independence raged. American vessels were capable of crossing the Atlantic and wreaking havoc on the vital Cork Harbour supply lines, while much closer to home, France and then Spain joined the American side and took arms against their frequent foe, Britain.
It was not unreasonable to think an invasion of Ireland could be undertaken to open up a new front in the war against Britain. In fact the event would transpire several times before the 18th century had passed. Over the centuries, superpowers had attempted to invade England and ‘The kingdom of Ireland’ was seen as a suitable back door.
The great sail ships of the age and the global outlook of these modern superpowers made Cork harbour a vitally important asset, with its ability to safely shelter entire fleets and provision them from the surrounding fertile countryside. That asset had to be protected, and Spike Island was to play a central, epic role in this undertaking.
The need for defence led to one of the largest construction projects ever undertaken in Ireland and the British Empire, and resulted in the colossus that is Fort Mitchel which dominates Spike Island to this day.
The first fortification on Spike Island consisted of a battery of cannons but its usefulness passed with the end of the American conflict. It was dismantled, but men like General Charles Vallancey were astute enough to know that peace was likely to be short lived.
He lobbied for and eventually got permission for a sizable 10 acre fort named Fort Westmoreland, which was built on the island in the early 1790’s. The designer of the fort and colorful character General Charles Vallencey was prolific in his lifetime, as an excellent architect, engineer and early Irish historian, a multi-published writer and husband to 4 wives and father to 14 children!
He was well aware of the need to defend the Empire from seaborne attack, having spent time living in heavily fortified Gibraltar where he learned of the techniques used in the great European coastal defensive locations, like those at Malta.
The first formal fort on Spike Island was not insignificant at ten acres in size, but Vallancey soon felt something even more impressive was required as a deterrent, with the emergence of Napoleon and a bitter war with France not going well.
The population of France outnumbered Britain’s 3 to 1 at the time, and the existential threat was palpable. He pushed for the funding for further protection, and permission was given for a military behemoth that stands tall to this day.
One of the largest military structures in the world…
The 24 acre star shaped Fort Mitchel that was started in 1804 is one of the largest military structures in the world. It was the cutting edge of military technology when it was completed fifty years later, representative of centuries of advancement and refinement in military thinking and coastal defence.
The designers chose the distinctive star shape design which had long replaced the straight square walls of Norman castles, which were big and impressive but an easy target for ever improving cannon fire. The star shape technique emerged around the 1500’s in Italy and it was used in cities like Pisa and by Michelangelo in his defences of Florence.
The points of the star shape, or ‘bastion’ as they are termed, meant defenders had overlapping arcs of fire all over the island, making the location one effective kill zone.
Should an enemy survive the run up the steep man made hill side known as a Glasis, and get close enough to the fort, flanking galleries were built into the sides of the bastion providing firing positions for defensive troops. These were effectively snipers galleries, allowing defenders fire on enemy troops from relative safety.
The whole fort itself was built with a low profile, setting it down into the islands summit in such a way that it can barely be seen by approaching enemy troops. This made it very difficult to target the fort with cannon fire from ships in the harbour, or small arms on the ground.
The British engineers shaved over 25 feet off the top of the island to achieve the feat, using enormous manpower, an army of one hundred horses, and in later decades, even dynamite to craft the island shape they desired!
Well over a million Pounds was spent on the structure by 1811, close to a Billion in today’s money, and as worked continued for several more decades from 1811 to 1864, this figure was well surpassed. This makes the structure potentially the most expensive building ever constructed in Irish history.
The size of Fort Mitchel Spike Island is immense by every global comparison, with the roof at Wembley stadium covering 11 acres, while Spike’s fortress expands to an impressive 24 acres. Most modern football stadiums would fit inside the forts walls twice. In fact the whole of Alcatraz Island, not just the prison, could fit snugly inside the forts walls, while you could fit four of Rome’s Colosseum inside!
You have to consider buildings like the Pentagon in America, with its 26000 staff and 28 acre spread, to find its equivalent
The vital strategic importance of Cork Harbour and Spike Island was being recognized in a fitting way, and that recognition would remain for 150 years. Winston Churchill visited the harbour as the then Head of the Admiralty and fought for its retention in the Treaty talks of 1921, holding on to the asset for British purposes.
When the island was eventually returned much later in 1938, Churchill thundered again of the areas importance, terming the forts at Cork Harbour, Berehaven and Lough Swilly as“the sentinel towers of the approaches to Western Europe”. This time, he failed in his efforts to retain the Treaty ports.
By 1820 the main work of the walls, bastions and some accommodation blocks were complete, before the war ended and funds for military building dried up entirely. By this time an impressive fortress had emerged fit to defend Cork harbour, unfinished and never fully armed, but undeniably fierce and if it became necessary, capable of defending an Empire.
On its completion the Fort could comfortable garrison several thousand men indoors, and many more if tented accommodation was used in outside spaces. But its military requirement dwindled and the fortress saw use as a prison during Ireland’s famine years, holding over 2400 inmates in what became the largest prison in the world in the 1850’s.
After the prison closed in 1883 it returned to solely British military use, with Colonel Percy Fawcett a famous serving soldier. When Ireland gained Independence in 1922 Britain insisted on retaining the vital fort as part of the peace Treaty.
It was 1938 before the island and fort was given back to Ireland, as part of negotiations in a trade war between the two countries, and Éamon de Valera watched as the Irish tricolour was raised for the first ever time over the fort. The Fort was renamed from Fort Westmoreland to Fort Mitchel following Irish Independence, after the Irish Nationalist John Mitchel who was a prisoner on Spike Island in 1848.
Today visitors can go through the forts impressive entrance walls to the enormous parade ground inside, and many of the original buildings and tunnels can be explored as part of a visit to Spike Island Cork, the epic island fortress and prison that protects Ireland’s Celtic sea.
REFERENCES – FURTHER READING
For the complete history of the fortificaiton of Cork Harbour and Spike Island see: Cal McCarthy – Cork Harbour – 2019, Merrion Press
John Harnett McEnery – Fortress Ireland: The Story of the Irish Coastal Forts and the River Shannon Defence Line – 2006, Wordwell
The Journal of the Royal Society of Antiquaries of Ireland – General Charles Vallancey 1725-1812 – 1993
Daniel MacCannell – Coastal Defenses of the British Empire in the revolutionary and Napoleonic Wars – 2021 – Pen and Sword Military
Paul M Kerrigan – Castles and Fortifications in Ireland 1485 – 1945 – 1995, Collins Press
Niall Brunicardi – Haulbowline Spike and Rocky Island – 1968, Cork historical guides
Other sources – Pues Occurrences / National Archives Ireland / National Archives UK