Page 33 - O Mahony Journal 2025

their castles and was built over the site of an ancient dun (stone fort) in 1217 with the edge of the
lake on one side and a cliff of Dunmanus Bay on the other.
It is one of the best preserved of the O Mahony castles and often called “Three Castles” because
of the three towers still standing from the original castle buildings, the main keep, a watch tower and
the entry tower at the lake. Both the extent of the remaining structure and the magnificent view over
Dunmanus Bay are good reasons for visiting this site that is a bit difficult to access. Indeed, the O
Mahony Society has gathered here in 1958, 1987, and more recently in 1996.
Dunmanus Castle was built by Donogh Mor O Mahony, a son
of Dermot ‘Buntach’ O Mahony, about 1460. Its remaining two
square main towers joined at one corner were so well constructed
that the full five-story height still overlooks Dunmanus Bay. It
suffered essentially the same fate as all the O Mahony castles
along this coast with confiscation shortly after the O Mahonys
showing support for the Earl of Desmond Rebellion in 1584 and
eventually was owned by Sir William Petty by the 1600s. This was
Eoin ‘Pope’ O Mahony’s favorite castle and Clan gatherings
were held here in 1963, 1971, 1984, and 1999. After his death a
plaque to memorialize him was placed on a wall.
Knockeen Castle. Before building Dunmanus Castle,
Donogh Mor O Mahony started constructing Knockeen Castle on the other side of the inlet to the
bay. This appears on many lists as one of the twelve O Mahony castles but it is uncertain that it was
ever completed. Supposedly an unknown individual came by during construction, recommended
it not be built where the sea would eventually undermine it, and it was abandoned for the present
Dunmanus Castle site.
Leamcon Castle (aka Black Castle) was built in the later
1400’s by Conor “Cabaice” O Mahony for his son Fineen Caol
“The Slender.” It stands on an island off the west entrance to
Toormore Bay across from Crookhaven. A few days after the
destruction of Dunboy Castle in 1602 a force attacked Leamcon
by a siege machine that protected the assaulters while they
worked to undermine the wall. The castle quickly surrendered
with the understanding that Chief Conor O Mahony could sail
to exile in Spain with others where they served in the Spanish
king’s Irish Brigade. While the unoccupied castle continued to
be owned by the O Mahonys, Dutch pirates infested the area
and occupied it. Captain William Hull, the vice-admiral of Munster from Devonshire, was sent to
deal with them in 1609. But without sufficient sea power to beat the pirates, he went into collusion
with them. In 1641 Hull had the castle burned to keep it from the Irish just as he had done with
Crookhaven Castle. The O Mahonys lost formal title in 1652 along with their other holdings. Recently
Leamcon Castle was purchased and rebuilt as a private summer home. This castle was the site of the
Clan Gathering in 1965 and 1975.
Rosbrin Castle was built in 1310 on land taken by the O
Mahonys from the O’Driscolls by the ninth century. It is sited
about two miles south of Ballyhob on the eastern part of Misen
Head Peninsula and is the most easterly of the O Mahony
Western Land castles. It was probably named after Bron,
the great grandfather of Mahon from whom the O Mahonys
descended. It was the home of Fineen O Mahony, a renowned
Latin and Greek scholar, and his large library during the 15th
century. Although his Gaelic translation of Sir John Mandeville’s
“Travels in the Holy Land” was found in a Rennes library in 1860,

33