Historical Society explores the history of star-shaped forts

BIRR Historical Society held their November meeting in Dooly’s Hotel, with a large turnout for the occasion. Chairperson, Bridget Sullivan introduced Stephen Callaghan, their speaker for the night. Stephen’s talk was entitled “A Star Shaped Fort in Crinkill”

Stephen, who hails from Dublin, is no stranger to the town of Birr where he has close family connections. He is an independent historian with an interest in Ireland’s military heritage and burial grounds. His many research interests include Birr (Crinkill) Barracks, the Leinster Regiment and the social histories of Offaly families who served in the British Army. He has published numerous articles, papers, and surveys on these and other topics.

Stephen’s talk on the night focused on the recently uncovered history of a remarkable star-shaped fort nestled in the Fourteen Acres adjacent to the Military Barracks in Crinkill, Birr and explores the fort’s origins, purpose and significance.

Stephen began his talk by addressing the question, what is a star shaped fort? These types of fort originated in Italy, are best described as star shaped fortifications having bastion or semi-bastion shapes and were often made from earth, brick or stone. The typical design of a fort began with a counter scarp that worked inwards; this was followed by a large moat type ditch, typically on a scarp or steep cliff like slope and finally the parapet where the heavy guns could be mounted.

There are a number of star shaped forts still in Ireland including notable examples such as Elizabeth Fort, Fort Mitchel, James Fort and Charles Fort in Cork, Magazine Fort in the Phoenix Park, Dublin and Duncannon Fort in Wexford to name but a few.

Stephen’s talk then took a diversion to focus on a similar fort used during the Paraguayan War (1864-1870) which was fought between Paraguay and the Triple Alliance of Argentina, Brazil and Uruguay. During the early stages of the conflict, Paraguay had brought over military advisors from Europe to train their armies. But one man in particular, George Thompson, a railway engineer by trade, made the biggest impact.

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George designed a bastioned fort which was located at a strategic bend on the River Paraguay, close to the city of Humaitá. This star shaped fort could observe and control all river traffic thus protecting Asunción, the capital city of Paraguay.

Following conflicts a little closer to home such as the Crimean War in the 1850’s, manuals and textbooks relating to star shaped forts were often published such as the "Elementary Principals of Fortifications" by John Thomas Hyde (1860) which explains the basic principles of military defensive structures, including the history and design of fortifications and the techniques used to construct them.

Getting back to Crinkill, Stephen went on to describe how during the course of his research he noticed unusual markings of possible earthworks around the quarry and pump house in Crinkill Barracks on the 1911 Ordinance Survey (O.S.) Maps. He thought these resembled the partial layout of a star shaped fort showing the outline of a bastion and a demi-bastion of a fort, these had not been visible on the earlier mid nineteenth century maps.

Stephen then travelled to the National Archives in London where he gleaned a lot of information; this was followed by visits to the Irish Army Archive, again to get access to more detailed maps and documents.

Armed with this archival information he reverted back to his geophysical surveys conducted at the site by the University of Bournemouth and the Irish Heritage School in early 2018. These surveys carried out by Ashley Green of Bournemouth University clarified there were several subsurface features especially around the quarry, where historic mapping showed the possible star shaped fort. Collectively, these findings seemingly confirming Stephen’s suspicions that a star shaped fort once existed at the site and was constructed somewhere between the mid nineteenth century and 1911.

While going through old newspaper reports, Stephen came across a reference in the King's County Chronicle (dated 5th September 1860) to the discovery of skeletal remains whilst the final diggings to the fort were being carried out. This clarified that the fort was completed between the end of August and early September 1860.

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As part of his talk, Stephen referenced a postcard from 1908 which showed the Fourteen Acres with a military encampment on it. If you look closely this postcard shows the banking of the fort, along with the stack of the gas works on its bottom left hand corner. Stephen showed a second photo from circa 1940 of the quarry and pumping station which included traces of the fort indicating some of the fort survived until at least this time.

The fort located in the Fourteen Acres at Crinkill Barracks would have been used for training purposes from the 1860’s onwards. However towards the end of the nineteenth century star shaped forts went out of style, mainly due to changes in the style of warfare, improvements in artillery (such as the breech loading gun) and new tactics being used in warfare.

It is not yet known exactly when the fort at Crinkill Barracks went out of use. What is known is that the quarry adjacent the partial star shaped fort supplied much of the stone used for the construction of Crinkill Barracks, and that it was in filled in during the 1950’s when new houses were erected in Grove Street. It seems likely that it was at this time that the final remains of the fort were removed.

It is amazing to think that a star shaped fort once existed in Crinkill, and that its history is now being rediscovered after a few little lines around a quarry were observed on the Ordinance Survey map of Crinkill Barracks!

A very interesting question and answers session took place after Stephens’s presentation. Following on from this, Chairperson, Bridget Sullivan concluded the meeting as she thanked Stephen and then thanked all for their attendance. She also acknowledged Dooly’s Hotel and their staff for the way the meeting room was presented and for their supply of refreshments afterwards.

Meetings will be held on the second Monday of the month in Dooly’s Hotel from October 2025 to April/May 2026. Next up in their series is Caimin O’Brien’s lecture on December 8th; when he will deliver a Marvellous Mystery Lecture. Please continue to note the change of venue.

There is a charge of €5 per night per lecture, or you can avail of membership for the year at €20 per adult or €30 per couple while students can attend for free.

If you would like to learn more about local history and archaeology, just come along to one of their meetings. All are most welcome. Alternatively, follow them on Facebook to know more about their activities.

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