Dempsey Surname Genealogy

is an anglicized version of O’Dempsey, the ancestor of
O’Diomsaigh. This family name came from the Gaelic word diomusach, meaning “proud” or
“haughty.” The O’Diomsaighs originated in the territory known as
Clanmalier, on the borders of what are now the Laois and Offaly
counties in Ireland.

Resources on

Dempsey Ancestry

The Annals of the Four Masters
recorded in 1193 the death of Dermot O’Dempsey, son of Cubgogda.
He was Chief of Clanmalier, for a long time Lord of Offaly, and the
founder of the Cistercian abbey at Monasterevan in county
Kildare. He also led the Leinster resistance against the
Anglo-Norman invasion in the 1170’s under Strongbow and defeated him in

The O’Dempsey territory, known as Clann Mhaoilughra, comprised a vast
area on both sides of the Barrow river and included the baronies of
Philipstown in Offaly, Portnahinch in Laios, and West Offaly in
Kildare. Lea
in Portnahinch, often occupied by the O’Dempseys, lay
in the center of these lands. Successive
O’Dempsey clan chiefs
held onto their territory.

the 16th
century, the O’Dempseys were on friendly terms with the English,
fighting with them in their attacks on the Irish clans at Mullamast in
1577, and their estates escaped confiscation. Terence O’Dempsey
was knighted in 1599 and created Viscount Clanmalier in 1631.

The O’Dempseys then switched sides. Three of their number were
prominent members of the Confederation of Kilkenny during Cromwellian
times. Loyalty to the Catholic King James II then resulted in the
forfeiture of all their lands in 1691. O’Dempseys had been
prominent in the Battle of the Boyne. Many O’Dempseys were
evicted from their homes and driven into neighboring counties such as
Tipperary. As one English commentator noted:

“Viscount Clanmalier was head of this
family at the Revolution of 1688. They are now obscure and sunk
into poverty and degradation.”

This clan history has most recently been recorded in Patrick Goode’s
2008 book The O’Dempsey Chronicles.

The Dempsey name is still strong in Laois and Offaly,
particularly in
their own homeland, but it has also spread throughout
Ireland. It
is quite common in county Antrim in Ulster where it may be an Irish
version of the Scottish name Dempster. There were a number of
Presbyterian farming families called Dempsey in the parishes of north
Antrim in the 19th century.

After the confiscation of the Clanmalier lands in
1691, Terence O’Dempsey left Ireland and settled in Cheshire. A
descendant of this line was General Sir Miles Dempsey, a commander of
the British Second Army during the D-Day landings in 1944.

James and Ann Dempsey were married in Liverpool in 1821 and James was a
timber merchant.

“The anecdotal account was that the
Dempsey family emanated from Ireland and that the daughters of James
and Ann were known as ‘the Dempsey beauties.'”

These Dempseys were part of a close-knit coterie of Liverpool merchant
families which often intermarried. Daughter Ann Dempsey married the
shipowner Thomas Holderness, daughter Frances the merchant William
Tarbet, daughter Louisa the Liverpool MP John Torr, and daughter Maria
the banker John Smith.

Many Dempseys came from Ireland to industrial Lancashire in the second
half of the 19th century, in search of jobs.

America. The earliest
Dempsey arrival in America was probably William Dempsey who came to
Philadelphia in 1726
as a young boy and made his home in
Virginia. Barnet Dempsey from county
Kildare came to Spartanburg, South Carolina sometime in the
1780’s. His son Levi moved onto Georgia.

Captain Michael
Dempsey, who emigrated to America in the 1830’s, was
from Lea parish in Laois and believed to be related to the Dempseys of
He enlisted in the US Army, fought in Florida in the Seminole Indian
War, and ended up farming in Catahoula parish, Louisiana.

More Dempseys arrived later in the 19th century via ports in the
northeast. Among them were:

  • Michael Dempsey and his sisters from Dublin onboard the Mount Washington to Boston in
    1849. They settled in the Boston area.
  • Lawrence Dempsey from Wexford onboard the Monongahela to Philadelphia in
    1850. Lawrence later married and they moved to Lee county,
    Illinois to farm. A Dempsey still lives on part of their farm

John Dempsey arrived with his
family from Tipperary in 1925. He rose through the political
ranks to be Governor of Connecticut from 1961 to 1970.

There were two famous Jack Dempseys in America who were world boxing

  • the first Jack Dempsey, known the Jack Dempsey the
    non pareil,
    came from Ireland but spent most of his boxing
    life in America. Sadly, he died young of TB.
  • the second,
    known as the Manassa Mauler, was born in Colorado from a family that
    had hailed originally from West Virginia. He lived on after
    retirement to run Jack Dempsey’s Restaurant in New

Australia. James Dempsey,
a United
Irishman, had been part of the Vinegar Hill rebellion in Wexford in
1798, resulting in his transportation to Australia. He was
granted his freedom in 1809 and his home became a spiritual and
communal center for the sizeable disenfranchised Irish Catholic
population of Sydney. He devoted his time, money, and effort in
later life to the building of the first Catholic chapel in Australia
for this community.

Among the later free settlers to Australia were:

  • Thomas O’Dempsey and his family on the Ballarat from Wexford in
    1828. They arrived in Melbourne.
  • Newly-weds James and Johanna Dempsey from Tipperary in
    1855. They came to Queensland and were one of the early settlers
    in Upper Freestone.

Dempsey Miscellany

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

Select Dempsey Names

, who died in 1193, was the first leader of the
O’Dempsey clan. He led the Leinster resistance to the
Anglo-Norman invasion under Strongbow.
James Dempsey built the first
Roman Catholic chapel in Australia.
(born John Kelly) was an Irish-born boxer called the
“nonprareil” becsuse no one could beat him. He died in 1895 at
the tender age of 33.
Jack Dempsey, known as the
“Manassa Mauler,” was world heavyweight champion from 1919 to 1926.

Select Dempseys

  • 8,000 in the UK (most numerous
    in London)
  • 10,000 in America (most numerous
    in New York)
  • 16,000 elsewhere (most numerous in Ireland).




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