Casino at Marino: Public’s first view of secret test-fire tunnels

Thompson submachine guns tested underground by leaders in War of Independence

A series of secret tunnels used by Michael Collins and other revolutionary leaders during the War of Independence to test-fire submachine guns will be opened to the public for the first time.


A series of secret tunnels used by Michael Collins and other revolutionary leaders during the War of Independence to test-fire submachine guns will be opened to the public for the first time next week.

The interconnecting chambers and tunnels run underneath the grounds surrounding the Casino at Marino, the 18th century miniature architectural masterpiece on Dublin’s northside.

They were originally excavated by James Caulfeild, 1st Earl of Charlemont, who built the Casino as an expression of the classical principles he had imbibed on a lengthy Grand Tour of Europe.

The long-disappeared formal paths, parklands and delights which were laid out by Charlemont around the Casino and the adjacent main residence, the now-demolished Marino House, would have been intended to achieve a healthy harmony of body and spirit, according to the principles of the Enlightenment.

Bathing pools

With that same objective, some of the underground chambers were designed as bathing pools. But the purpose of others is still unclear.

“We don’t know conclusively what they were all used for,” said Pauline Kennedy, supervisor guide at the Casino. “There are lots of different theories. But tunnels always excite the imagination.”

Ms Kennedy said Charlemont probably started building the tunnels to connect with Marino House, but ran out of money before completion. He died a bankrupt in 1799.

Charlemont was afflicted by various ailments, some of which he believed were due to the unfortunate consequences of an amorous escapade on his Tour. A lady who thought she had been slighted by him had slipped something poisonous into his food - or so he thought.

His personal physician, Dr Charles Lucas, had also written a treatise on the health-giving benefits of water, so he was probably following instructions when he built the tunnels. “He would take a constitutional in his parkland, and then go underground to one of his grottos to restore his constitution with cold water,” said Ms Kennedy.

Still mysterious

Nowadays the grottos look more like cellars, and not particularly appealing ones at that. With their odd nooks and crannies of differing heights and sizes, dimly lit from above by small grilles and vents, the tunnels remain mysterious. But they also have a more recent historical resonance, which a new exhibition at the Casino explains.

The longest tunnel runs almost to the perimeter of the current grounds. It was used in 1921 by Volunteers from F Company of the Dublin Brigade to practise firing the first Thompson submachine guns that had arrived into Ireland as a result of fundraising efforts by Harry Boland in the US.

Witness statements confirm that shortly after the arrival of the guns, Michael Collins, Oscar Traynor, Richard Mulcahy, Ginger O’Connell and other rebel leaders used the tunnel for firing practice and were delighted with the results.

However, the tunnels are only a few feet below the ground. The neighbouring local Christian Brothers alerted the rebels that the supposedly secret target practice could be heard all over Marino and further afield.

“We had heard stories that Michael Collins had used our long tunnel to practise firing,” Ms Kennedy said. “And we knew that the Mauser rifles and ammunition unloaded from the Asgard in Howth in 1914 had probably been stored here. With that background of revolutionary activity, I went trawling through the Bureau of Military History archives,” she said. She found several witness statements confirming that many prominent revolutionary leaders had used the tunnels for firing guns.

A photograph of F Company, 2nd Battalion, Dublin Brigade of the Irish Volunteers, which was based in the Fairview area, was taken at a reunion of 83 members of the company sitting on the south lawn of the Casino some time between 1939 and the early 1940s.

Photograph recreated

This Sunday afternoon, the Casino will be recreating that photograph and has put out a call to any descendants of F Company who would like to be included.

The Casino will be closed for a commemorative event on Sunday. But from next Monday, August 22nd, as part of Heritage Week, visitors can explore the story of the long tunnel in an exhibition, Tunnel Vision: Going Underground at Casino Marino, as part of the regular paid tour visit at the Casino.

After Heritage Week, tunnel access is on Thursday to Saturday inclusive only, and the usual admission charges apply. Entry restrictions can apply due to weather/operational conditions.

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