The castle was built in 1185 by
Prince John of England, then first Lord of Ireland, during his
first expedition to Ireland. Ardfinnan and Lismore appear to be the first castles built and occupied by a member of the English Crown in Ireland. To guard the northern border of
Waterford from the Gaelic kingdom of
Thomond, John's father
Henry II of England proposed Ardfinnan and
Tybroughney on the fording of the river Suir, with
Lismore on the
Blackwater as key positions to erect castles, following his visit to these sites with
Hugh de Lacy in 1171. He may have handed management of Ardfinnan to the
Knights Templar in this year as he did with other sites downstream in Waterford and
Wexford. Ardfinnan and Lismore were scenic
early-Christian monastic sites on
Saint Declán's 5th century pilgrim path developed into important abbeys by
Saint Mochuda around 632 AD. John arrived in Waterford in April 1185 and built Ardfinnan castle on the former site of
Ardfinnan Abbey, twelve miles directly north of its sister at Lismore Castle, constructed around the same time that year. Lismore Castle was also built over its former abbey.
Maurice de Prendergast protected the royal castle of Ardfinnan or “Castrum de Harfinan” One of these is signed "
King of Limerick" and may be the first instance a member of the English crown titled himself a king of territory in Ireland. Numerous raiding parties were launched from the castle into the surrounding north and western territories. Ardfinnan is subsequently referred to as an administrative
cantred, under Philip of Worcester. Philip had been Governor of Ireland from 1184 and would subsequently replace Hugh de Lacy who died in 1186. As land was secured to the north, Philip was granted the barony of Kiltenenan in 1194, of which
Cahir Castle, 4 miles north of Ardfinnan Castle, became the chief seat. Ardfinnan Castle under Norman control, an enquiry led by King John in 1206 reasserted its ownership by the English Crown. The
cantred of Ardfynan (Ardfinnan) was again granted in 1215 to Philip of Worcester by
Henry III, but three years later was again a possession of the English Crown. Philip's nephew, William of Worcester paid a fee of contract for the cantred of Ardfynan in 1225 to Henry III, indicating the continued royal status of Ardfinnan Castle and its surrounding cantred. The castle had a continued presence of the monastic military order of the Knights Templar, and later the
Knights Hospitaller. The Hospitaller's later credit Philip of Worcester and the king for the origin of their estate at Ardfinnan, after it passed to them from the Templars but it is not known if they existed here simultaneously. In 1177 he gave Prendergast Castle in
Wales to the Knights Hospitaller. The Templars had two watermills on the River Suir as part of their first chartered land grants in Ireland in 1172 and may be indicative of their presence at Ardfinnan for its monastic watermill and fertile land in the centre of the mountain valley. While the Templars managed this important pass into Waterford and between the ecclecsiatical centres of
Cashel and Lismore, they constructed the castle's surviving round tower or Templar preceptory in the late 12th or early 13th century. The tower has been identified as a chief preceptory of the order when they first came to Ireland according to McCurtin's Annals. Following dissolution of the Templars in 1312, their estates were transferred to the Hospitallers and according to the Hospitaller's register of chapter acts 1326–1339 were in possession of
"the burgages in the town of Arfinan (Ardfinnan)
and the church and all the tithes and appurtenances thereof" and as part of a charter agreed to a free church with appointment of a chaplain to minister daily. The scale of the economic success of the Hospitallers is evident when Ardfynan was exempted from customs and sanctions by an act of the
Parliament of Ireland passed in 1449. An inquisition in 1588 showed that after the death of the same Bishop of Waterford and Lismore, the Manor of Ardfinnan, comprising 80 acres and a mill, was transferred to the hands of Elizabeth I..|250x250px == Cromwellian siege ==