Dillon in Ireland is an Anglo-Norman name that arrived with Prince John in 1185 and took root in Westmeath, where the family’s lands became known as Dillon’s Country; a separate Gaelic family in Munster and Galway, the Ó Duilleáin, also came to be written Dillon. The Dillon family crest designs in our Dillon Irish family gifts collection set the name on the Irish National Tartan, whether your Dillons came from Westmeath or from Kerry.
Quick answer: Dillon comes from a Norman-French personal name, rendered Díolún in Irish. Sir Henry Dillon received large grants from King John in Westmeath and Annaly, his descendants were barons of Kilkenny West, and the family later produced the Viscounts Dillon, the Earls of Roscommon, the Barons Clonbrock and the colonels of Dillon’s Regiment in France. In Kerry, Limerick, Clare and Galway, Dillon can instead stand for the Gaelic Ó Duilleáin.
What Does the Dillon Surname Mean?
According to Rev. Patrick Woulfe’s Irish Names and Surnames, Dillon began as a Norman-French personal name, formed from an old Germanic name, Dill, Dillo or Dilli, with the French diminutive ending -on. The root survives in England in the surname Dill, and a second diminutive of it, Dilkok, turns up in the Patent and Close Rolls of Ireland. Early Irish records write the family as Dylun and Dilloun. In Irish the name is Díolún, and Woulfe notes that the older spelling, Díolmhain, looks like an attempt to make it resemble an Irish word.
That makes Dillon a name that entered Ireland ready-made, carried by a Norman household rather than coined from an Irish ancestor. The Irish spellings were fitted to the sound of the French name, and Woulfe’s early forms, Dylun and Dilloun, show clerks working toward the Dillon spelling that the family’s later peerages made familiar.
Who Were the Dillons of Dillon’s Country?
Woulfe records that the Dillons came to Ireland at the time of the Anglo-Norman invasion and that Sir Henry Dillon received from King John large grants of land in Westmeath and Annaly, “known in later times as Dillon’s Country.” Later genealogies date Sir Henry’s arrival to 1185, when he came over with Prince John. His descendants were barons of Kilkenny West, a Westmeath barony that takes in part of Lough Ree and that logainm.ie lists as Cill Chainnigh. The barony had been formed by 1542, and its older names were recorded as Maherquirke or Dillon’s Country.
A branch of the family also settled in County Mayo. Theobald Dillon built up estates in the barony of Costello and was appointed sergeant-at-arms for Connacht and collector of the composition rent for Connacht and Thomond in May 1582. He was created Viscount Dillon of Costello-Gallen in March 1622. The Dictionary of Irish Biography places his probable death at Killefaghny, County Westmeath, on 15 March 1625; the often-quoted 1624 date may reflect confusion between old and new calendar styles. A second line produced the Earls of Roscommon, created on 5 August 1622 for James Dillon, who had been made Baron Dillon in 1619; Wentworth Dillon, the 4th Earl, was a courtier, poet and critic who died in 1685. A third, descended from Gerald Dillon, became Barons Clonbrock in County Galway in 1790.
What Was Dillon’s Regiment?
Woulfe notes that in the seventeenth and eighteenth centuries the Dillons were distinguished in the service of continental powers, and the best-known example is Dillon’s Regiment. In 1688 Theobald, 7th Viscount Dillon, raised two regiments for James II, one commanded by his son Henry and the other by his son Arthur. Arthur’s regiment landed at Brest on 1 May 1690, while the Williamite war was still being fought in Ireland, and it became one of the regiments of the Irish Brigade in the French army.
Arthur Dillon, born in County Roscommon in 1670, led it through the Nine Years’ War and the War of the Spanish Succession, at Cremona in 1702, Cassano in 1705, Castiglione in 1706 and Toulon in 1707. He was made a lieutenant-general in 1706 and received the Jacobite title Earl Dillon in 1721. He died at Saint-Germain-en-Laye on 5 February 1733. The regiment that carried the family name fought at Fontenoy in 1745 and was disbanded in 1793, in the upheaval of the French Revolution. At home, Henry, 8th Viscount Dillon, obtained the reversal of his outlawry in 1694 and later served as Lord Lieutenant of County Roscommon.
Is Dillon Always an Anglo-Norman Name?
No. Woulfe lists a Gaelic surname, Ó Duilleáin, written in older English records as O Dullaine, O Dyllane and Dillane, which he describes as common in Kerry, Limerick, Clare and Galway and often hidden under the English form Dillon. It is a variant of Ó Dalláin, “descendant of Dallán,” a diminutive of dall, blind, which Woulfe calls a formerly not uncommon surname throughout the south of Ireland.
So Dillon families in Kerry, Limerick, Clare and Galway can belong to the Gaelic Ó Duilleáin, while the Dillons of Westmeath, Mayo and Roscommon are the places tied to the Anglo-Norman line. The O’ prefix belongs to the Gaelic name, which clerks wrote as O Dullaine or O Dyllane, and not to the Norman Díolún.
Where Are Dillon Families Found in Ireland?
The Anglo-Norman Dillons are tied to a clear set of places: Kilkenny West and Kilfaughny in Westmeath, Costello and Gallen in County Mayo, County Roscommon, where Arthur Dillon was born and the earldom took its title, and Clonbrock in County Galway. The Gaelic Dillons belong to Kerry, Limerick, Clare and Galway. The political Dillons of later centuries kept a western link: John Dillon sat for East Mayo from 1885 to 1918, and his son James Dillon died at Ballaghaderreen, County Roscommon, in 1986. A family’s parish and townland are the best guide to which of these Dillon stories is theirs.
How Can I Research Dillon Family History?
- IrishGenealogy.ie: civil birth, marriage and death records, plus church registers for several dioceses.
- National Archives of Ireland 1901 and 1911 census: search Dillon by county and compare Westmeath, Roscommon and Mayo households with those in Limerick and Kerry.
- Griffith’s Valuation: mid-nineteenth-century landholders, useful for placing a Dillon family in a townland.
- National Library of Ireland Catholic parish registers: baptisms and marriages, many earlier than civil registration.
- National Archives of Ireland: wills, land and estate papers, useful for the landed Dillon lines of Westmeath, Mayo and Galway.
- logainm.ie: the Irish and historic forms of townland and barony names such as Kilkenny West.
Look for Dillane, Dullane and O Dullaine next to Dillon in older Munster records, since clerks wrote the Gaelic name in whichever form they heard.
Notable Irish Bearers of the Dillon Name
- Theobald Dillon, 1st Viscount Dillon (probably died 1625), administrator and landowner, created Viscount Dillon of Costello-Gallen in 1622.
- Wentworth Dillon, 4th Earl of Roscommon (died 1685), courtier, poet and critic.
- Arthur Dillon (1670–1733), born in County Roscommon, commissioned a colonel in the French army on 1 June 1690 at the head of Dillon’s Regiment, and a lieutenant-general from 1706.
- John Blake Dillon (1814–1866), Young Irelander who founded The Nation with Thomas Davis and Charles Gavan Duffy in 1842, went into exile after 1848 and was elected MP for Tipperary in 1865.
- John Dillon (1851–1927), born in Blackrock, County Dublin, a leader of the Plan of Campaign, MP for East Mayo from 1885 to 1918 and last leader of the Irish Parliamentary Party in 1918.
- James Dillon (1902–1986), TD for Donegal and then Monaghan, Minister for Agriculture in 1948–51 and 1954–57, and leader of Fine Gael from 1959 to 1965.
Frequently Asked Questions About the Dillon Name
What is Dillon in Irish?
For the Anglo-Norman family it is Díolún, with the older spelling Díolmhain. For the Gaelic family of the south and west it is Ó Duilleáin, a form of Ó Dalláin.
Is Dillon an Irish or a Norman name?
Both. The best-known Dillons descend from Sir Henry Dillon, who came with Prince John in 1185, and their name is Norman-French. In Kerry, Limerick, Clare and Galway, Dillon often stands for the native Irish Ó Duilleáin.
Which county is the Dillon family from?
The Norman Dillons belong to Westmeath, where the barony of Kilkenny West was Dillon’s Country, with later branches in Mayo, Roscommon and Galway. The Gaelic Dillons come from Kerry, Limerick, Clare and Galway.
What was Dillon’s Country?
It was the name for the Dillon lands in Westmeath and Annaly, given to Sir Henry Dillon by King John. The Westmeath barony of Kilkenny West, formed by 1542, was earlier known as Maherquirke or Dillon’s Country.
Are Dillon and Dillane related?
In Munster they can be. Dillane is one of the English forms of Ó Duilleáin, and Woulfe notes that the same family was often written Dillon.
Who founded Dillon’s Regiment?
Theobald, 7th Viscount Dillon, raised it for James II in 1688. His son Arthur Dillon took it to France in 1690 and commanded it in the Irish Brigade.
Dillons of Kilkenny West stock and Dillons of the Kerry and Clare Ó Duilleáin share one English spelling, and our Dillon Irish family gifts collection carries it on woven and printed blankets, a mug, the House of Dillon garden flag, a framed ornament and a Celtic harp T-shirt.