O’Reilly Surname Genealogy

O’Reilly is derived from the Gaelic O’Raghailligh,
meaning descendant of Raghaillach (from ragh, a “race,” and ceallach meaning
“gregarious”). The story goes that Raghaillach was killed at the
Battle of Contarf in
1014 while fighting alongside Brian Boru.
His descendants, the
O’Reilly sept, followed Celtic traditions with their chief being
inaugurated at an ancient stone circle on Seantomon hill outside of
town.  Today it is O’Reilly more in Ireland, Reilly more outside. And Reilly has often become Riley.
Select O’Reilly Resources on The Internet

O’Reilly Ancestry

The O’Reillys
were the most powerful sept of the old Gaelic kingdom of
Breffny which comprised present-day Cavan and surrounding
counties. For a time they lay under the shadow of the
stronger O’Rourke clan. They also fell foul of Norman
incursions into their territory.

However, a new chief, Giaolla Iosa
O’Reilly, re-established O’Reilly control in the early 1300’s and
helped develop Cavan as a thriving market town. The O’Reillys
were able to maintain their position for over two hundred years.
Their stongholds were Clogh Oughter castle and Tullymongan
hill outside of Cavan town.

The O’Reilly were widely involved in trade at this time. They
created their own coinage by “clipping” English coins and at one time reilly was a term for Irish
money. It has also been suggested that they lived well, as the
phrase “the life of Reilly” suggests.

The English were eying Breffny in Tudor times. They
captured Cavan town in 1600. Edmund O’Reilly of Kilnacrott was
killed at that time, the last of the O’Reilly chiefs of Breffny, and
lost his estates.
In the 1640’s, during the Irish rebellion, the O’Reillys – led by
Edmund’s son Myles
the Slasher
– retook Clogh Oughter castle and were
temporarily in power
again. But Clogh Oughter fell to Cromwell in 1653 and the English
process of dispossession and confiscation of lands continued.
Hugh Reilly of Cavan supported the luckless Stuarts in 1690 and
followed James II into exile.

The O’Reilllys suffered for their Catholic faith during the penal
times. Some “wild geese” became mercenaries abroad. Many
O’Reillys emigrated later. In Ireland the largest numbers are in
Dublin. O’Reillys are still numerous in what was Breffny – Cavan
and neighboring Longford.
The name is also quite common in Fermanagh and Monaghan. Some 60%
are called O’Reilly and 40% Reilly.

Spain and Austria. Alejandro
left his home
in Baltrasna, Meath during the penal times to fight for the Spanish
army in the Irish Brigade. A Field Marshal and Count, he was sent
to Cuba in 1769 to quell disturbances there. One of Havana’s
streets is called Calle Orely and his descendants are still to be found

Colonel Edmund O’Reilly commanded O’Reilly officers in the Spanish and
Austrian armies during the 1700’s. Count Andrew O’Reilly of
Westmeath was a Field Marshal in the Austrian army who, as Governor of
Vienna, had the humiliation of surrendering the city to Napoleon in

England. O’Reillys and Reillys came to England in the 19th
century and primarily to Lancashire. James Reilly was in
Manchester sometime by the 1820’s. He and his sons were
cabinet-makers and skilled ones too. Their trade expanded until
by the late 1800’s they had even begun to export their furniture.

But many Reillys arrived and lived in poverty and
overcrowding. Eight members of a Reilly family together with
eleven lodgers were recorded as living in a tiny cellar dwelling on
John Street in Manchester during the 1850’s.

America. O’Reilly
emigration to America also stepped in in the 19th century. Many
left during the famine times. John Riley came in the 1840’s,
started off fighting for the US Army in the Mexican War, and then
left them to fight on the Mexican side. Andrew O’Reilly came to America
via Canada. As also did James O’Reilly:

“Articles about James O’Reilly who
emigrated between 1849 and 1852 suggest that it took him eight weeks to
come by a boat that was shipwrecked and landed in Newfoundland.
He came to Troy, New York where he worked as a farm laborer for three
years. Perhaps he, like many other Irish emigrants, sent money
home to his family, enabling his brother Michael to follow him to
America and perhaps helping to keep those who stayed at home alive.”

John Boyle O’Reilly was a man who made the journey to America through
unusual routes. He had been transported to Australia in
1867 because of his involvement in militant Fenian groups. But he
escaped, made his way to Boston, and became a supporter of Irish causes
there and the well-respected editor of the Pilot newspaper.

Alexander O’Reilly, a descendant of the O’Reillys in Cuba, grew up in
Philadelphia and became a well-known doctor. He was personal
physician to President Cleveland and surgeon general to the US Army in
the early 1900’s.

Canada. Peter O’Reilly,
the son of an Irish father and English mother, left Ireland in 1859 for
the opportunities that might be presented in the new western colony of
British Columbia. He prospered there in forty years of Government
service. In 1868 he bought a large home in Victoria which
was lived in by his descendants until 1975. It is now known as
Point Ellice House and is preserved as a museum.

Australia. O’Reillys and
Reillys who came to Australia included:

  • Joseph Reilly, who having retired from the British army came to
    Western Australia from Meath in 1853 with his wife Mary and settled in
  • Peter O’Reilly who arrived in New South Wales from Ulster in
    1865. His grandson Bill, nicknamed “Tiger,” was the great
    spin bowler of the Australian cricket team in the 1930’s.
  • and Thomas O’Reilly and his family who left their native
    Roscommon for Melbourne on the Lady
    in 1875. They settled in Numurkah.

The Green Mountains on Australia’s Gold Coast was first settled in 1911
by an O’Reilly family. They took up a number of small dairy farms
before consolidating their holdings around what is now an
internationally famous guesthouse in the rainforest.

O’Reilly Miscellany

If you would like to read more, click on the miscellany page for
further stories and accounts:

O’Reilly Names

Giaolla Iosa O’Reilly restored the O’Reilly position in Cavan in
the early 1300’s and founded the Franciscan Abbey.
Myles O’Reilly, known as Myles
the Slasher, became a folk hero in Ireland for his stand against the
English during the Irish rebellion of the 1640’s. He died in
battle in 1644.
was an international rugby player for Ireland who
became the CEO of Heinz Corporation.
Paddy Reilly is one of
Ireland’s best-known balladeers.
Bill O’Reilly has been a prominent
face on American
TV today through his O’Reilly Factor
show on Fox TV.

Select O’Reillys and Reillys Today

  • 29,000 in the UK (most numerous
    in Lancashire)
  • 34,000 in America (most numerous in New York)
  • 52,000 elsewhere (most numerous in Ireland)





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