LETH CUINN AND LETH MOGALeth Cuinn
Leth Cuinn, “Conn’s Half,” the northern half of Ireland.
The Connachta derive their name from Conn (Dál
Cuinn, “Division of Conn”) and from them is named
the province of Connacht in the west of Ireland. The
Uí Néill emerged from the Connachta as an indepen-
dent group by the late seventh century. The Ulaid
(Ulstermen), who would seem to have exercised over-
lordship over the northern half in the protohistoric
period, suffered massive defeats in the battles of Moira,
County Down, in 637 and Faughart, County Louth, in
- They never recovered. Their place was taken by
the Cenél nÉogain who gradually moved eastward
across the Foyle from Inishowen and dominated all of
the north by the mid ninth century, making the Air-
gialla their vassals and dominating the Dál Riada of
northeast Antrim, the Dál nAraide (Cruithin) of mid
Antrim, the Dál Fiatach of Down, and many other
groups that had formerly been under the Ulaid. In
Connacht the Uí Briúin of County Roscommon came
to dominate the province supplanting the Uí Fiachrach
and Uí Maine, as well as a multitude of earlier popu-
lations. The southern Uí Néill had conquered the mid-
lands from the Shannon to the sea absorbing many
older population groups. The clan Cholmáin became
the dominant group among them. Both branches of the
Uí Néill sought to dominate Leth Moga—indeed it was
essential if they were to claim the high kingship—
although major campaigns against Munster were rare
before the eighth century. Although Leinster was
within the cultural area of Leth Moga in the seventh
century, by the eighth century it was dominated by the
Uí Néill. Máel-Sechnaill mac Máele-Ruanaid, king of
the southern Uí Néill, was the first high king with real
power. He campaigned in Munster and was the first
high king to reach the south coast in 858. The position
of Osraige, lying between Leinster and Munster, was
ambiguous, but in 859 it was alienated to Leth Cuinn.
There were Munster challenges to the Uí Néill:
Cathalmac Finguinne in the eighth century, Fedelmid
mac Cremthainn in the ninth century, Cormac mac
Cuilennáin in the tenth century, and Brian Bóruma in
the latetenth century to early eleventh century. Of these
Brian was the most successful. In the post-Viking period,
the emergence of Dublin as an international trading
port and the feudalization of Irish society brought about
a gradual reorientation of politics in Ireland. The old
pattern of north-south conflict was no longer as impor-
tant as the competition to control the wealth of Dublin.
Medieval kingdoms were emerging in both halves of
the country, led by powerful families such as Ua Briain
in Munster, Ua Conchobhair in Connacht, Mac
Lochlainn and Ua Neill in Ulster, and Mac Murrough
in Leinster. Many of the major battles of the twelfth
century took place in the midlands with control of
Dublin as the ultimate goal. As a result of this pressure,
the Uí Néill kingdoms of the midlands were greatly
weakened. The arrival of the Anglo-Normans in the
late twelfth century was the final blow to the ancient
divisions since they conquered and settled large areas
in both halves of Ireland.Leth Moga
Leth Moga, “Mug’s Half,” “The Servant’s Half,” from
Mug Nuadat, “Servant of Nuadu,” otherwise known
as Eógan, eponymous ancestor of the Eóganachta,
the main dynasty of Munster. The capital of Leth
Moga was Caisel (Cashel in Tipperary), a borrowing
of the Latin castellum (castle, fortress), and tradition
claims that it was founded in the fifth century. This
may be read against the background of Irish settle-
ment within the borders of the Roman Empire in
Wales and Cornwall. Cashel was distinct from other
tribal capitals in that, despite underlying pagan ele-
ments, its foundation story (“The Finding of Cashel”)
is strongly Christian and many, but not all, of its kings
were also clerics. The Eóganachta were spread through-
out Munster—the main branches were the Eóganachta
Áine, East Limerick; Eóganachta Glendamnach,
North Cork; and the Eóganachta Chaisil, Tipperary.
The kingship of Munster circulated among the vari-
ous branches of the Eóganachta until it was virtually
monopolized by the Eóganachta Chaisil from the
mid ninth century onward. The wide settlement of
the Eóganachta across Munster assured control of
their many subject peoples. Several Munster kings
campaigned against the Uí Néill. Cathal mac Finguine
harassed the midlands and Leinster from 733 until
738, but although the Uí Néill accepted his strength
within Munster, he was not allowed control of Leinster.
Fedelmid mac Crimthainn, king (820–847) and
abbot, provided a serious challenge to the Uí Néill
invading the midlands and Connacht in the 830s and
840s. He was no respecter of churches sacking both
Clonmacnois and Kildare, as well as many others.
In 840, he camped at Tara, indicating his ambition
to achieve political dominance, and became involved
in Armagh politics toward the same end. He
attempted to hold the Óenach Carman in 841 to
demonstrate his overlordship of Leinster, but suf-
fered a massive defeat. Cormac mac Cuilennáin, king
and bishop of Cashel (902–908) again attempted to
win political supremacy, but was defeated at Belach
Mugna in Leinster in 908. With Cormac’s death the
power of the Eóganachta collapsed. Their place was
taken by an obscure group that rose to power through
their ability to control the portages on the lower