The visitor to Fermoy never fails to be impressed by the hill of Corrin - a great, rounded hump on the southern skyline, crowned by an immense heap of stones (a "carn"or cairn, from which it gets its name), and by a massive modern cross in stone that can be seen for many miles around.
On the Ordnance Survery Maps, it is called "Carn Tierna"; the Pipe Roll of Cloyne calls it "Tigearnaig Mic Degaid"- and the Book of Lismore names it "Carn Tigearnaig Mic Degaid"- whoever Tighearnach Mac Deaghaidh may have been.
From the summit there is a wonderful view to the south and east over the ancient territory of Ui Liathain, and to the north and west over the ancient territory of Fermoy.
This Fermoy territory - (Fir) Magh Feine or Caoilli - is a great peneplain of fertile land over ten miles wide from north to south, and twenty miles in length from east to west. It extended from the border of the modern county of Waterford almost to the site of present-day Mallow town, and was bounded on the north by the Galtee Mountains and the Ballyhourn Hills and on the south by the Nagles Mountains.
It is drained southwards by the Awbeg, Funcheon and Araglin Rivers and many a lesser stream, into the noble Munster Blackwater which flows eastwards close to the flanks of the Nagles on the south.
The hills and mountains that hem in the territory belong to the east-west Armorican foldings of the Palaesoic Era. The old Red-sandstones are now exposed on all their slopes, while great thicknesses of Carboniferous Limestones are found on the valley floors, particularly on those of the Awbeg and Funcheon.
Keating, in his "Forus Feasa ar Eirinn" gives a romantic account of the origin of Fermoy as a political division of Munster. In brief it is as follows:
"When Cormac Mac Airt reigned in Tara (3rd Century A.D.) he found that the tributes he was receiving from the provincial kings were not sufficient to support his court. All Munster was ruled by a single provincial king at this time - Fiachaidh Euilleathan - but it had often been divided, both before and afterwards, into the Two Munsters; so one of Cormac's advisers suggested to him that he should demand a double Tribute from Fiachaidh Muilleathan, in order to ease his financial difficulties.
Cormac, therefore, advanced into Munster with a large army to enforce his demand for the double tribute, but was stoutly resisted by the Munstermen.
Certain Scottish Druids, who accompanied Cormac, cast spells on Munster so that the wells dried up, and man and beast suffered grievously.
Fiachaidh was compelled to bring in a famous Druid from Valencia Island, Mogh Ruith by name, who would not stir a hand to help until his fee was solemnly guaranteed to him.
The spells he cast were so powerful that Cormac's army retreated in confusion, and Mogh Ruith entered into possession of his reward which was "dá thriúchadh céad"- "two thrity-hundreds" of the fairest land in Munster."
And the land he chose, according to Keating was "dá thriúchadh céad Fhear Moighe", also know as "Caoilli". Local tradition says that he took up residence on Cathair Druinne, over opposite Corrin, near present-day Kilworth Camp, where he could keep watch over most of his new domain.
