McMahon Surname Meaning, History & Origin

McMahon Surname Meaning

McMahon is an anglicized form of the Old Gaelic MacMathghamhna, a patronymic from the byname Mathghamhain, meaning “bear.”  Two distinct septs of this name existed in Ireland, one in county Clare and the other in and around present-day Monaghan.

The first specific recording of a McMahon in Ireland – dating from the 1170’s – was, however, the McMahon name adopted by Reginald FitzUrse after he had fled to Ireland following the murder of Thomas a’Beckett. 

McMahon Surname Resources on The Internet

McMahon Surname Ancestry

  • from Ireland (Clare and Monaghan)
  • to France, England, America, Canada and Australia

Ireland.  There were two distinct septs and territories for the McMahons in Ireland.

The first belonged to Thomond, now county Clare.  They were descended from Mathghamha, son of Murtagh Mor O’Brien, king of Ireland, who died in 1119.  The lands of Corcabaskin, Moyarta, and Clonderlaw in west Clare were considered their territories.

Here the McMahon name is still numerous.  The remains of Carrigaholt castle dominate the harbor at Loop Head in county Clare.  Teige McMahon, the last of the lords of Corcabaskin, lived there.  He died in 1601 after the battle of Kinsale, accidentally killed by his own son.

The other McMahons became lords of Oriel in the 13th century (Oriel being an ancient kingdom encompassing Armagh, Monaghan, and parts of Down, Louth and Fermanagh).  The first of these McMahons was Niall McMahon ladrannaibh or bandit.  Chiefs of the clan were crowned at Lough Leck in present-day Monaghan.

Their history over the next three hundred and fifty years appears to have been one of continuous fighting, not only with other septs but amongst themselves.  However, it was the English that caused their eventual demise.  After the Irish uprising of 1641 had been crushed the McMahons were no longer listed as landowners in Monaghan.  Their last chieftain, Hugh Oge McMahon, had in fact been a lieutenant colonel in the Spanish army.

McMahons struggled after the Gaelic order ended.  A few joined “the wild geese” and others began to emigrate in the 19th century.  In 1890 the McMahons were most plentiful in Ireland in Clare, Monaghan (where they were the third ranked surname), Limerick, and Dublin.

France.  John McMahon, an Irish doctor from Limerick, had come to France to escape the English penal laws in Ireland.  He married into the French aristocracy and became the Marquis de MacMahon.  His son fought on the American side in the Revolutionary War; and his grandson Patrice was a French general who went on to be a Marshal of France and the first President of the Third Republic in the 1870’s.

England and Scotland.  McMahons came to Lancashire and to Glasgow in the 19th century because of the industry and the jobs there.

Philip McMahon, for instance, came to Manchester in the 1830’s, marrying Ann Connor there.  One family line in Scotland  began with James McMahon who came to Glasgow in the 1820’s and married Mary Lynch there in 1828.  Steve McMahon, born near Liverpool, played for Liverpool football club in the late 1980’s.

America.  Bernard McMahon, driven to exile by the state of Irish politics. settled in Philadelphia in 1802 and  made his name there in the cultivation of rare plants.  Helped by his Irish wife, he built up one of the biggest seed businesses in the United States and had the evergreen shrub, Berberis mahonia, named after him.

An earlier McMahon arrival from Ireland had been Richard McMahon sometime in the 1740’s.  He had settled initially in Wilmington, Delaware before moving onto Kentucky.  His son William Friend McMahon senior was killed by Indians in Ohio in 1793.  His grandson William Friend junior was an itinerant Methodist preacher, passing through Kentucky, Arkansas, and Louisiana before making it to Texas in the 1820’s.

More McMahons came in the 19th century.  Among them were:

  • Martin McMahon from Waterford, who arrived in New York with his parents via Canada in the early 1840’s.  He was a Union army general during the Civil War and later a lawyer and US Marshal in New York.
  • William McMahon from Belfast, who came in the 1850’s to Wisconsin to raise pigs (however, his pigs were wiped out in an epidemic).  William fought on the Union side in the Civil War.
  • Patrick and Mary McMahon, who arrived after the Civil War and settled in Jersey City.  Patrick and his sons were carpenters.
  • and James and Mary McMahon from Clare, who arrived in the 1860’s and headed west to Davenport, Iowa.

Edward McMahon came over from Ireland, probably in the 1880’s, and settled in Lowell, Massachusetts.  His son Joseph started a plumbing business and Joseph’s grandson was Ed McMahon, Johnny Carson’s TV sidekick.

Then came the brothers Edward and James (Jess) McMahon from Galway to New York in the early 1900’s.  Jess began promoting professional wrestling matches in the New York area in the 1920’s.  He was the forebear of three generations of famous McMahon wrestling promoters.

Canada.  Patrick McMahon, a Catholic priest, had come out to Quebec in 1817, after having completed his studies in county Laois.   He ministered to the growing Catholic presence there until his death in 1851. Also moving to Quebec from Laois was a recent widow, Ellen McMahon, and her nine children in 1837.  They eventually came to live just outside Toronto where two of her sons learnt the trade of coopering.

Patrick and Ellen McMahon from Limerick came to Canada in 1841 and settled in Finch township, Ontario.

Australia.  James “Butty” McMahon arrived as a child with his parents from county Clare in the 1860’s.  He founded his own freight company which became one of the largest in Sydney.  He died in 1914 a wealthy man:

  • his son James was well-known as a rugby footballer before taking over the family business; but another son William frittered his life away with heavy drinking and gambling and died in 1926.
  • yet it was William’s son Billy McMahon who had the long career as a Liberal politician and was briefly in 1971-72 Prime Minister of Australia.
  • while Billy’s son Julian is an actor who has appeared in both Australian and American films.

McMahon Surname Miscellany

Niall McMahon Ladrannaibh or Bandit.  Niall Mac Mathghamhna is said to have been descended from Mathganna, the original lord of Fernmaige who died in 1022.  He is cited in the Irish annals from 1196 to 1207.  It seems then that he had been waging his own private war against the Anglo-Norman intruders for some forty years.

History has recorded him as ladrannaibh or bandit.  But without this “bandit,” there would certainly have been little chance of the McMahons becoming kings of Oriel.  His actions led to the rise of the McMahon kings who subsequently arose to that position when Eochaid became the first “formally recorded” McMahon king of Oirghialla around 1250.

Lough Leck and the Coronation Stone of the McMahon Kings.  It was on a hill by Lough Leck, three miles southwest of Monaghan town, in Kilmore parish, that the McMahons first arose and where they were crowned as Kings of Oriel.

According to the traditional accounting of the event, the ceremony always took place on a Tuesday.  Mass was said.  The chief-elect was then admonished by his pastor concerning the duties and ethics of office.  A procession was formed, led by a priest.  Then came the chief-elect, kinsmen, and clergy.

Midway along the route three sturdy youths, representing the Three Collas, maintained a mock combat.  When they reached the summit of the hill, the chief-elect took his seat on the stone and swore on the Domhnach Airgid.  A golden rod, forged in the smithy at Clones monastery, was placed in his hand.

The new chieftain then stood on the McMahon stone and looked in three directions, representing the Blessed Trinity.  He walked off in the fourth direction.  He then took off his cloak and his sword and the Abbot anointed him.

Then one of his men cut his arm.  He lay down and his blood mixed with the earth.  Next he sat down on the stone and sent four black doves off to the four winds.  At this bagpipes began to play and the procession formed again and set off for the church.  Midway to the church, young girls approached and sprinkled earth and salt and wheat.

The McMahon stone measured six feet five inches long by four feet four inches broad.  On the stone was the impression of a foot, said to be the foot of one of the first McMahon kings. 

Maura Rua MacMahon.  One noted McMahon was Maura Rua MacMahon, whose husband, Conor O’Brien, was killed by Cromwellian forces in 1651.  They lived in Leamaneh Castle, near Kilfenora in county Clare.

When enemy soldiers brought back her husband’s body from the battlefield, she is said to have shouted at them from a window of the castle: “Take him away. We want no dead men here!”

John McMahon’s French Makeover.  Towards the end of the 17th century after the defeat of the catholic English king James II, a great many Irish emigrated.  This exodus was popularly known as the “‘Flight of the Wild Geese.”

There were three McMahon brothers in Limerick.  Maurice, the oldest, joined the Spanish King’s army, then that of Louis XIV; Michael, the second brother, stayed in Ireland and became the Bishop of Killaloe; while John, the youngest, went to medical school in Reims before going to practice at Autun in Burgundy.

At that time the Morey brothers owned the Château de Sully nearby, but were finding life rather dull.  One of the brothers, who at that time was some sixty years old, decided to jolly things up a bit by marrying their young cousin, Charlotte Le Berlin from Eguilly.

Charlotte, however, was only 19 years old and she certainly did liven things up.  Her husband may have been youthful but his health suffered and the doctor had to be called in frequently.  And it so happened that this doctor was a charming Irishman who called himself Jean Baptiste de MacMahon.  In fact he was so charming that he ended up marrying widow Charlotte.

Louis XV accorded him the title of Marquess.  Jean Baptiste and Charlotte had seven children and they lived at Sully happily ever after.

Charles Patrick Mahon.  Scholars have reached the conclusion that the Charles Patrick Mahon who called himself “The O’Gorman Mahon” was of the Clare McMahons.

Spurning a career in law, he embarked on one which took him all over the world.  He became an intimate of Louis Philippe and Talleyrand in France.  The Czar of Russia appointed him to his bodyguard.  He soldiered in the Far East, South America, was an admiral in the Chilean navy, a colonel in Brazil’s army, and a colonel in Napoleon III’s regiment.

He re-entered politics in Ireland as a supporter of Parnell.  He unwittingly led to the downfall of Parnell by introducing him to Katherine (Kitty) O’Shea.  The hero of thirteen duels, many of them fatal to his opponents, he died in London in 1891 at the age of 91, vigorous to the last, although it is not possible to authenticate all of his adventures.

William Friend McMahon at Fort Recovery, Ohio.  Major William Friend McMahon was attached to the Legion of the United States, an early version of the US Army.  On June 30, 1793, just outside of the gates of Fort Recovery, a pack-horse train led by him was attacked by 2,000 Indians.  Major McMahon was killed and the rest of the survivors fled into the fort.  The Indians then made a general attack on the fort.  The battle raged for two days, but Fort Recovery was not taken.

Ed McMahon’s Background.  Ed McMahon, the man who coined the famous phrase “Heeeere’s Johnny,” was born to an Irish-American family in Detroit, Michigan in 1923 (the reason he was born there was that his parents had stopped there on the way to a fundraising job).

Ed’s father was a promoter, entrepreneur, traveling salesman, and fundraiser for charities and hospitals and clubs – by selling punch boards and running bingo games.  This was how McMahon got his first gig, calling bingo.

Ed grew up in New England and used to spend some of his summers with his dad’s parents, Joseph and Katherine McMahon of Lowell, Massachusetts.  His grandfather, a master plumber, was the founder of the J.F. McMahon Plumbing Company.

McMahon Names

  • Niall McMahon was the bandit who fought against the Anglo-Normans for forty years and is seen as the forebear of the McMahons of Oriel.
  • Patrice, Comte de MacMahon, was a Marshal of France and its President in the 1870’s.
  • Jess McMahon was the American founder in 1925 of World Wrestling Entertainment.
  • Billy McMahon was a long-serving Australian minister and briefly, in 1971-2, Prime Minister.
  • Ed McMahon was Johnny Carson’s sidekick on TV’s Tonight Show.

McMahon Numbers Today

  • 16,000 in the UK (most numerous in London)
  • 15,000 in America (most numerous in New York)
  • 29,000 elsewhere (most numerous in Ireland)




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Written by Colin Shelley

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