UÍ DÚNLAINGEthe late ninth century, Tadg mac Diarmata (d. 865) and
his brother Cairpre (d. 876). Although both these kings
were killed feuding with their own relatives, most of
Cairpre’s descendants in the tenth century were kings
of Uí Chennselaig, and were gradually able to increase
their power despite internecine strife and intrusions from
outside south Leinster. Diarmait mac Máele-na-mBó
of Síl nOnchon inaugurated a new period of success
for the dynasty, firstly by consolidating his hold on
Ferns and the rich royal demesne thereabout, and then
eliminating rivals for the kingship of Uí Chennselaig.
The power of the Uí Dúnlainge kings had declined as
a result of attacks by Uí Néill, Vikings, and the kings
of Osraige, and Diarmait mac Máele-na-mBó was able
to take the kingship of all Leinster in 1042. While he
was engaged on his campaigns, his son Murchad acted
as regent in Leinster, maintained Uí Chennselaig dom-
inance over Uí Dúnlainge, conducted border raids
against Mide, and focused his attention particularly on
the control of Dublin, which was increasingly inte-
grated into the Leinster province. Murchad’s obit in
1070 calls him
rí Laigen & Gall
( “king of Leinster
and the Foreigners”), and he was buried at Dublin.
His descendants took the family name of Mac Murchada
(Mac Murrough), and though they retained the Leinster
kingship they were unable to challenge for the high
kingship of Ireland, though Diarmait Mac Murchada
played a pivotal role in the politics of the twelfth
century.
M
ARK
Z
UMBUHL
References and Further Reading
Byrne, Francis J.
Irish Kings and High-Kings.
London: B. T.
Batsford, 1973; Reprint, Dublin: Four Courts Press, 2001.
O’Byrne, Emmett.
War, Politics and the Irish of Leinster,
1156–1606
. Dublin: Four Courts Press, 2003.
Smyth, Alfred P.
Celtic Leinster. Towards an Historical Geog-
raphy of Early Irish Civilization A.D. 500–1600.
Dublin:
Irish Academic Press, 1982.
See also
Diarmait mac Máele-na-mbó; Dublin;
Laigin; Leinster; Mac Murchada, Diarmait;
Mac Murchada; Uí Dúnlainge; Uí Néill;
Viking Incursions
UÍ DÚNLAINGE
Uí Dúnlainge was one of the most important popula-
tion groups and dynasties in early medieval Leinster.
Uí Dúnlainge considered themselves to be of the Laigin
and to be descended from Dúnlaing, grandson of Bres-
sal Bélach, the ancestor also of Uí Chennselaig. Uí
Dúnlainge occupied fertile land in north Leinster,
including the Liffey valley and Kildare plains. Uí
Dúnlainge initially owed their rise to the decline of
earlier Leinster dynasties in the face of the expansion of
the southern Uí Néill, and in the seventh century they
drove the Uí Garrchon and Uí Enechglaiss across the
Wicklow mountains. The first significant king of Uí
Dúnlainge was Fáelán mac Colmáin (d. 666 or earlier)
who defeated competitors from the rival dynasties of
Uí Máil and Uí Chennselaig to attain the kingship of
Leinster; he was also allied with the southern Uí Néill.
From the mid-eighth century, Uí Dúnlainge monop-
olized the kingship of Leinster. Three of the sons of
Murchad mac Brain (d. 727), Dúnchad, Fáelán, and
Muiredach, reigned in turn after him as kings of Leinster.
These kings were progenitors of the most powerful
branches of Uí Dúnlainge in the following three cen-
turies: Uí Dúnchada, Uí Fáeláin, and Uí Muiredaig. Uí
Dúnchada were settled between the lower Liffey and
the Wicklow mountains, their territory later extending
to the outskirts of Dublin. Their center was at Liamain
(Lyon’s Hill, Co. Kildare), and several members of the
family enjoyed the abbacy of Kildare. Uí Fáeláin set-
tled to the southwest, with their center at Naas. Further
south dwelt Uí Muiredaig, with their base at Maistiu
(Mullaghmast, Co. Kildare); they had links with the
church of Glendalough.
The kingship of Leinster rotated between these
groups, and this pattern of a “circuit among the
branches” of an Irish dynasty has been used as one of
the models of Irish kingship. For all the apparent neat-
ness, the succession was often accompanied by feud
and fratricide. Additionally, though later king-lists call
many of these dynasts kings of Leinster, the contem-
porary evidence of the annals sometimes gives them
lesser titles such as “king of Uí Dúnlainge,”
rí Iarthir
Liphi
(“king of western Liffey”), or even “king of
Naas.” This may be due to the dominance that the Uí
Neill periodically asserted over them, forcing them to
submit and give hostages. The southern Leinster kings
must often have rejected Uí Dúnlainge overlordship,
and as time went on the authority of the Uí Dúnlainge
kingship was eroded.
From the ninth century, domination of Leinster
became a main point of contention between the kings
of Uí Néill and the kings of Munster. A highly signif-
icant development in this period was the establishment
of a Viking base at Dublin in 841. Soon the Dublin
Vikings controlled a substantial hinterland north and
south of the Liffey estuary (Fine Gall) and were a
considerable threat to their neighbors. However, inter-
nal dissensions among the Dublin Norse facilitated an
attack in 902 by Cerball mac Muirecáin, Uí Fáeláin
king of Leinster, in alliance with the king of Brega,
which drove the Vikings from Dublin for fifteen years.
Cerball Mac Muirecáin also fought against Cormac
mac Cuillenáin in 908 and married Gormfhlaith (d. 948),
said to have been the latter’s widow.