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William Caldbeck (1733-1803) & the Moyle Park Gunpowder Mills

Gunpowder was key to the Grueber fortune.

An account of the amateur architect and barrister who built a gunpowder mills for the Irish Volunteers in Clondalkin, County Dublin, in 1782, only for them to explode five years later.




In 1782 the banks of the River Camac in the south of County Dublin were to become home to a grand, new gunpowder mill. This was built a couple of miles downriver from the existing Arabin-run mills at  Corkagh, close to the site of the present day Mill Shopping Centre in Clondalkin village.

The owner of the new mill was William Caldbeck, an amateur architect, King’s Counsel barrister, Treasurer of the King’s Inns and leading light of the Irish Volunteers. [i] His descendants lived at Moyle Park House (now Moyle Park College), Clondalkin, from 1780 until shortly before the First World War. The origin of the family is unknown but it is possible that that they descend from a mason and bricklayer called William Caldbeck who was employed by Trinity College, Dublin, between 1686 and 1722.[ii]

William Caldbeck of the Clondalkin mills was born in 1733 and clearly prospered when he ‘took silk’ to become one of Ireland’s legal elite. He became a member of the Mary’s Abbey Knot of the Friendly Brothers in 1765, when his address was given as French Street, Dublin. [iii] By 1780 he had amassed enough money to start work on Moyle Park House.[iv] That same year he also built a foundry ‘at his own expense’ with the express purpose of ‘casting brass canons for the use of the volunteers of Ireland’.[v] Caldbeck was a major patron of the Volunteers, the militia raised by Ireland’s aristocracy and landed gentry in direct response to the withdrawal of so many regular British soldiers to fight in the American Revolutionary War. Henceforth Irish shores would be defended from French and Spanish invasion by Volunteers corps such as the Lawyer’s Artillery of which Caldbeck was colonel.[vi]

Work must have still been in progress at his mansion and foundry when Colonel Caldbeck began building a new mill at Moyle Park to supply gunpowder to the Volunteers. [vii] The foundation stone was laid on 28 May 1782 by James Caulfield, the first Earl of Charlemont, commander-in-chief of the Volunteers.[viii] At the earl’s side were Lord Delvin (later 7th Earl of Westmeath) and Caldbeck’s fellow lawyer Barry Yelverton (later Viscount Avonmore), who became Attorney General that same year.[ix] It was a lively ceremony to which an unspecified number of the volunteers marched all the way from the Phoenix Park, where they had been reviewed by Colonel Allen. Mr. Caldbeck then threw a lavish party in his garden at which guests dined on ‘every substantial dish fitting for soldiers, with abundance of wine, Irish porter and native whiskey.’ [x] This may explain why a cavalryman called Thomas Braughall ‘fell from his horse and unfortunately broke his thigh’ midway through the festivities. [xi]

Caldbeck’s Mills were up and running within less than two years. On 11th May 1784 Saunders Newsletter carried an advertisement pointedly headlined ‘Irish Manufacture’ which stated that ‘a large quantity of all kinds’ of gunpowder made by Caldbeck was now ‘ready for Sale, as cheap and superior in Quality to any imported.’ Prospective buyers and ‘merchants desirous to Export’ were advised to call into 6 Bishop Street, Dublin, during the morning, where they were assured of ‘terms equally advantageous with any Foreign.’ Six months later, Francis W Warren, a linen draper based at 92 Grafton Street, placed a similar advertisement offering Caldbeck’s gunpowder ‘on the lowest Terms for Ready Money.’[xii]

An abbreviated version of this story appears in ‘CORKAGH – The Life & Times of a South Dublin Demesne 1650-1960’ by Turtle Bunbury. Published by South Dublin County Council in May 2018, the book is available via the Local Studies Collection at the County Library in Tallaght, so people can either visit the Library or contact them at 01 4597834.

Gunpowder was still exceedingly dangerous to work with. The Pinneau mill blast may have ‘shivered’ windows in Naas but a considerably bigger explosion was to rock the Caldbeck mills on 23 April 1787. According to a widely reprinted report from Dublin written a few days later, the cause of ‘the melancholy catastrophe’ was a stove used to dry the powder which overheated and caused five or six barrels to catch fire. The fire quickly spread to the loft of the Corn Mill where another 260 barrels of gunpowder were stored. The ensuing ‘violent concussion of the air’ and ‘tremendous explosion’ were felt for several miles around, particularly to the east where ‘the earth seemed to shake from the very centre, and many persons adjacent were deprived of light for a few moments, by the violence of the shock. Houses were unroofed, windows broken, and pewter and other things cast with violence from dressers.’

‘The effects upon the spot itself were horrible beyond description – the whole building was torn up from its very foundations and hurled into the elements. When the cloud of smoke had dispersed, not a vestige was to be see of it; not a trace that a building had ever stood upon it; and the person that never seen the works could scarcely bring himself to believe that such complete desolation could be effected in so short a space. Ponderous ruins, tons in weight, were cast to the distance of four or five fields, and the ground was ploughed into furrows where large stones, hurled by violent impetuosity, had touched.’

‘All the fish in a pond contiguous were found floating on the surface of the water. Trees were broken in the middle; and the remainder of the works, which were totally detached from this place, present a frightful spectacle of ruin and are little more than a heap of rubbish; the walls tattered, and the roof drove in.’

Amazingly only two men died in the explosion. As the London Chronicle observed (May 5-8, 1787), the explosion took place on St. George’s Day and, given that ‘the greater part of the persons employed there are Englishmen,’ all bar two employees had taken the day off to commemorate their patron saint. One of these two luckless men was blasted into in an adjacent quarry adjacent, ‘his head horribly shattered … The other has not yet been discovered, although diligent search was made ever since. It was supposed that he was blown to atoms, and scattered in different places. Five or six men were wounded – one it is thought mortally. It would seem as if the immediate hand of Providence protected the inhabitants of the neighbourhood from the effects of this dreadful accident. Upon no other supposition can the circumstance of so few lives being lost from such an unparalleled explosion be accounted for.’

The losses sustained by William Caldbeck were ‘very considerable’ although, as the Freeman’s Journal observed, his ‘country-house, which lay contiguous, being to windward, received little or no injury whatever.’ Nonetheless, the public were urged to lament ‘the destruction of a great national undertaking set on foot and brought to perfection by the public spirit of Mr. Caldbeck.’

The Huguenot artist Gabriel Beranger, who arrived in Ireland in 1771, later attributed the destruction of the medieval church across the road to the explosion but amazingly the Round Tower in Clondalkin survived utterly unscathed.[xiii] This becomes all the more remarkable given an observation by the legal historian F. Elrington Ball that ‘the concussion was felt so severely even in Dublin that it caused the fall of a stack of chimneys on Usher’s Quay’.[xiv]

The Freeman’s Journal reported on a number of other extraordinary consequences.

‘A quantity of fish were taken up dead in the adjoining river and Grand Canal, so far as the effects of the explosion could operate.

A fox was unkennelled in the Hill of Belgard, and ran with such velocity as to lose the power of fight, whereby he was taken with great care by the boatmen at the Canal and is now chained in the stores.

The glasses, china, windows, etc. of the Monasterevan [sic] boat on the Canal were broke to pieces; but what is more surprising, a large cat was found at the threshold of Ballyfermot Castle, still alive, but with its hair singed off, which was killed by one of the servants to put an end to its misery and this is a fresh proof, that thrown at this prodigious difference from the mills, it is not easy to rid a cat of existence.

But what will surprise somewhat more, Mrs. Margaret Donovan, a respectable dairywoman at the East end of Clondalkin, at hearing the explosions, not only got rid of an old rheumatism with which she was afflicted, but an aching tooth dropped out; and her eldest son, an otherwise acute lad of seventeen, was restored to the full use of the tympanum of his ears, and the articulation of his tongue, and immediately cried out, “Oh mother! Is that the Napper Tandy?” And of this Mrs. Donovan has made oath before Justice Jones, who declared that it had a contrary effect upon him, for he had lost his speech on the occasion.

Many other marvellous effects are said to have happened, which shall be conveyed to the public as soon as they are received.’

The short-lived mills were recalled by a commemorative pedestal on the lawn near the gate lodge at Moyle Park, succinctly inscribed ‘CALDBECK’S POWDER MILLS 1783’.[xv]

It is thought that Caldbeck rebuilt the mills soon afterwards. Certainly the demand for gunpowder was showing little signs of abating by 1793 when the Royal Horse Artillery was formed under the authority of the Board of Ordnance to provide artillery support to the Cavalry.

Caldbeck had many other things to focus on. In 1791 he was elected a member of the Dublin Society and became a member of their fine arts committee.[xvi] His proposers for Society membership were the gallantly named Christmas Weekes and the unfortunate Thomas Braughall who had tumbled from his saddle at Moyle Park nine years earlier. As treasurer of the King’s Inns Society, Caldbeck drafted its charter of incorporation in 1792. An unfortunate episode took place that same year when he was hired by Mary Amyott to prosecute her husband Dr Francis Amyott, Professor of Modern Languages at Trinity College, on a charge of wife-beating. Caldbeck failed to convince the jurors that his client’s case was legally valid.

In 1794 Caldbeck submitted designs for the hall and library at the King’s Inns on Henrietta Street but these were rejected in favour of those submitted by James Gandon.[xvii]

Saltpetre, one of the three core ingredients of gunpowder.

On 26th August 1799, a year after the collapse of the United Irishmen’s rebellion in Leinster, Saunders Newsletter published a notice that the gunpowder mills ‘lately worked by Wm. Caldbeck’ were to be let, along with ‘four sets of runners and bedstones, graining machine and stove, with every necessary for refining petre and sulphur and charring coal, with magazines, large stores, and sheds, in the completest order.’ Thomas Gelling was on hand at the mills to show potential buyers around. Ultimately the mills evolved into the Clondalkin Paper Mills, established in the early 19th century by Thomas Seery and Son.

William Caldbeck died aged seventy on 6th September 1803 and was buried in Clondalkin three days later. Two weeks later, the Irish nationalist Robert Emmet was hanged and beheaded near St. Catherine’s Church on Thomas Street, where the Caldbecks owned property. The Caldbecks were connected to Emmet through Sarah Curran, Emmet’s sweetheart, who was a first cousin of Anne Curran, the wife of William Caldbeck’s grandson Francis.

A subsequent investigation into the King’s Inns accounts found that miscellaneous records for 1803 and 1804 were missing. A half-hearted case for fraud was launched against William Caldbeck’s estate in 1806 but ran on inconclusively before it finally petered out in November 1821.

By his marriage to Anne Keatinge, William Caldbeck had three sons. His descendants remained at Moyle Park through the 19th century until Major William Roper-Caldbeck, a grandson of Francis and Anne, sold it sometime before 1902 to Major Thomas James Ryves, a retired police officer from India. Vacated in 1920, the house was occupied for a period by Patrick Nugent before the Marist Brothers opened it as a school in 1957.




The town hall in Kells County Meath was originally designed as a bank in 1853 by William Caldbeck’s great-grandson, the Dublin architect and civil engineer William Francis Caldbeck (1824-1872), with whom he is sometimes confused.

[i] Burke’s ‘Landed Gentry of Ireland’ (1904), 81, and Maurice Craig, ‘The account book of William Caldbeck, architect’ in Design and Practice in British Architecture: Studies in architectural history presented to Howard Colvin, Architectural History 27 (1984), 421.

[ii] William Caldbeck worked for Trinity College from 1686; the last payment to him while he was still alive was made on 3 January 1718. He had died by 1722 when his executors were paid £141.2s.10d. for his work on the last part of the long wall in Patrick’s Well Lane. The following year ‘Caldbeck & Quinn’ – Thomas and Joseph Caldbeck and Francis Quinn – were paid for brick and stonework on the new library. References: The Dictionary of Irish Architects, Irish Architectural Archive. All information in this entry is from TCD muniments, MUN P/2/2, 3, 7, 8, 11, 12, 13, 16, 18-20, 22-7, 30, 32, 33, 36, 47, 48.

[iii] William Caldbeck was proposed as a Friendly Brother on 4 Jan 1765, balloted for 5 July and joined on the same date. The pre-1770 minute books for the Mary’s Abbey Knot do not survive.

[iv] As well as his lands at Moyle Park, Caldbeck appears to have owned Larch Hill, Whitechurch, Co. Dublin, and further lands at Kilmashogue and Thomas Street.

[v] The Hibernian Magazine, Or, Compendium of Entertaining Knowledge, James Potts, May 1782, p. 280.

[vi] In June 1783 Caldbeck united with the other leading members of the south Dublin community to offer substantial rewards for anyone willing to come forward and testify about illicit activity in the area.

[vii] “Ball, F Elrington, ‘A History of the County Dublin’, p. 119-120.

[viii] Ibid, p. 120.

[ix] Yelverton, who built Fortfield House, Terenure, a few years later, became Lord Chief Baron of the Exchequer in 1783.

[x] The Hibernian Magazine, Or, Compendium of Entertaining Knowledge, James Potts, May 1782, p. 280.

[xi] Ibid, p. 280. A Braughall who was a member of the United Irishmen may have been noticed in R B McDowell’s ‘Personnel of the United Irishmen’. He may also be mentioned extensively in Tom Bartlett’s book entitled ‘Revolutionary Dublin 1795 – 1801’ which contains the letters of Francis Higgins, editor of the Freeman’s Journal. With thanks to Patrick Gageby.

[xii] Dublin Journal, 4 December 1784. “Gunpowder of the First Quality made by William Caldbeck, Esq, at his Mills near Clondalkin. Now selling on the lowest Terms, for Ready Money, by Francis W Warren, Linen Draper, No. 92, Grafton Street, Dublin.’

[xiii] John D’Alton,’ The History of the County of Dublin’, p. 719. Lennox Barrow, in ‘The Round Towers of Ireland: A Study and Gazetteer’ (Academy Press, 1979), p. 82, thought the collapse of the church as claimed by Beranger was ‘unlikely’ but I am not so sure.

[xiv] Ball, F Elrington, p. 119-120. As the Freeman’s Journal observed: ‘The wind being at N.N.W. when the above incident happened, all the damage that was done was between Clondalkin and the city.’

[xv] Rev. C. T. McCready, ‘Clondalkin Parish – Extracts from Parish Registers’ (Ireland Genealogy Project Archives, 2007).

[xvi] He was elected a member of the Dublin Society on 28 April 1791, his proposers being Thomas Braughall and Christmas Weekes. The Dublin Society awarded him a £40 premium for planting 10 acres under timber, 3 July 1800. He was appointed a member of the fine arts committee on 24 July 1800.

[xvii] E. McParland, James Gandon (1985), 165,204. Bryan Bolger also records his ordering work on some stables near Aungier Street in 1798. [NA/PRO Bolger MSS. 1A/58/128.