MAC MURCHADA, DIARMAITother. This was particularly true after Diarmait’s
joint action with Mac Lochlainn’s principle rival—
Tairrdelbach Ua Conchobhair—in destroying Ua
Briain at Móin Mór. The same year, following his
victory in Munster, Diarmait sent Mac Lochlainn the
hostages of Leinster, seemingly of his own free will.
In was a shrewd political move designed to avoid the
enmity of Mac Lochlainn without preventing Diarmait
from acting with Ua Conchobair when it suited him.
In this way, Diarmait maximized the chances of secur-
ing his interests.
In 1152, with his control over Osraige newly
secured, Diarmait involved himself in the affairs of
Mide. In concert with Ua Conchobair and Mac
Lochlainn, he attacked Tigernán Ua Ruairc (d. 1172),
the king of Bréifne, and notoriously kidnapped Ua
Ruairc’s wife, Derbforgaill. Both Gaelic and Anglo-
Norman sources report this tale with relish, but they
vary on the question of motive. The Annals of
Clonmacnoisereport that Diarmait wished “to satisfie
his insatiable, carnall and adulterous lust.” The Song
of Dermot and the Earl, however, portrays the unfor-
tunate Derbforgaill as a pawn in Diarmait’s power
game with Ua Ruairc:
Dermot, king of Leinster,
Whom this lady loved so much,
Made pretence to her of loving,
While he did not love her at all,
But only wished to the utmost of his power [to be
avenged on Ua Ruairc].It was supposedly in retaliation for this that Ua Ruairc
insisted on Diarmait’s expulsion from Ireland, which
led directly to the appeal to King Henry II. In fact,
Diarmait’s flight from Ireland came some thirteen
years after the kidnapping. Moreover, in 1166, Ua
Ruairc was an ally of Ruaidrí Ua Conchobair, whose
father Tairrdelbach had been allied with Diarmait in
the attack on Ua Ruairc in 1152. Neither of these
facts has, however, prevented the two events’ being
directlyconnected in popular imagination. The histo-
rian F.J. Byrne snubbed both this interpretation and
Derbforgaill with the memorable comment that “[she]
may have been fair, but was certainly forty.” Instead,
he attributed Ua Ruairc’s hostility to his long-standing
rivalry with Diarmait over Mide. Nonetheless, there
can be little doubt that the Derbforgaill affair added a
personal edge to an already acrimonious relationship.
The death of Tairrdelbach Ua Briain in 1156 altered
the political situation in Ireland. Muirchertach Mac
Lochlainn was now without serious rival, and Diarmait
threw his lot in with him; Tigernán Ua Ruairc was
soon associated with the new king of Connacht,
Ruaidrí Ua Conchobair. It was at this time that
Diarmait began to take a serious interest in the Ostman
cities of Leinster. His great-grandfather, Diarmait mac
Máel-na-mBó, had set a precedent of taking the king-
ship of Dublin in 1052, but it was some time since
more than a nominal submission had been wrung from
what was emerging as the capital of Ireland. In 1162,
aided by Mac Lochlainn, Diarmait forced Dublin to
submit and according to the annals “obtained a great
sway over them, such as was not obtained for a long
time.” It was his connection with the foreigners or
“Gall” of Dublin, and not his appeal for Anglo-Norman
aid, that won for Diarmait the nickname “Diarmait na
nGall.”
Diarmait already had a long association with Dublin.
He had founded the Augustinian nunnery of St. Mary
de Hogges there in 1146, and sometime after 1161
established the priory of All Hallows on the site now
occupied by Trinity College, Dublin. This relationship
is instructive in terms of assessing his subsequent
appeal to King Henry II. Through trade and its coveted
fleet, Dublin had a centuries-old relationship with
Wales and England. Previous kings of Leinster, in
claiming authority over the city, were thereby brought
into this transmarine network [see Anglo-Irish rela-
tions]. But one does not have to dig so far into the past
for an association. In 1165, the native Welsh chronicle
reports that Henry II hired a fleet from Dublin to fight
in his abortive Welsh campaign of that year. Diarmait,
in control of Dublin, surely had knowledge of this,
possibly indicating a connection with Henry II dating
from only one year prior to Diarmait’s flight from
Ireland in 1166.
Diarmait’s power was now bound up with Mac
Lochlainn, and when the latter fell in 1166 Diarmait’s
enemies, Ua Conchobair and Ua Ruairc, rapidly
moved against him. The men of north Leinster and the
Ostmen of Dublin took the opportunity to rebel, and
Diarmait was forced to retreat to his heartland of
UíChennselaig. He then took the decision to sail to
Bristol and seek out Henry II [see Anglo-Norman
Invasion]. He was back in Ireland with a small group
of Anglo-Norman adventurers by 1167, and Ruaidrí
Ua Conchobair, now king of Ireland, allowed him to
retain his homeland of Uí Chennselaig. Diarmait was,
however, set on greater things and had promised his
daughter in marriage and the succession to Leinster to
the earl of Pembroke, Richard de Clare (Strongbow),
who arrived in Ireland in 1170. By the time Diarmait
died at his capital of Ferns around May 1171, his
Anglo-Norman forces—although not yet entirely
secure—had destabilized the political situation in Ireland,
causing other Irish kings to go into rebellion and shat-
tering the power of Ruaidrí Ua Conchobair. They were
successful enough to bring Henry II to Ireland late in- With that royal expedition, the history of the
English lordship of Ireland began.