1990:084 - LIMERICK: King John's Castle, St Mary's Parish, Limerick

Introduction
King John's Castle is a polygonal, keepless castle of 13th-century origin, situated on the east bank of the River Shannon. It was incorporated into Limerick's medieval defences on the north-west side of the King's Island or Englishtown. The monument's circuit has survived quite well to the present day except on the Nicholas Street side. Here, the demolition of the eastern curtain wall and much of a 17th-century bastion occurred between 1793 and 1823, more than 50 years after the castle had been converted for use as a military barracks. Many of the barracks buildings constructed within the castle limits during the 19th century were in turn replaced by Corporation housing in the 1930s.

As part of the plans to revitalise the area between Thomond Bridge and the Cathedral, it was decided to undertake a major restoration of the castle in order to clearance of the housing and the last remaining barrack promote it as a tourist attraction. This work involved building, cleaning and repairs on the extant walls of the castle itself and construction of a two-storey interpretive centre.

To allow this work to proceed, excavation commenced in February 1990 with the aim of defining the line of the east curtain wall and the demolished east and north sides of the bastion. The excavation was confined to an area measuring approx. 40m north-south by 20m east-west. Financed by the Heritage Precinct Fund, work continued throughout 1990 and early 1991. Because of the on-going nature of the excavation, some interpretations offered below are likely to alter as more information comes to light.

The excavation
Substantial remains of the curtain wall and the bastion were revealed quickly by machine. In addition, excavation around these walls resulted in the discovery of a series of features relating to the occupation of the site prior to the 13th century as well as considerable evidence relating to mid 17th-century siege activity.

The evidence for pre-Norman settlement falls into two categories. The first consists of features belonging to a defence system, the existence of which had a profound impact on the manner in which the east curtain wall was constructed. The second includes features of a more domestic nature in the form of three house-like structures and the remains of post-and-wattle fences.

The features in the first category included a clay rampart or bank revetted by a limestone wall. This had an excavated length of 10.1m, with a maximum surviving height of 1.7m. At its base was an external limestone pathway, about 1m in width, beyond which lay a ditch 11.4m wide and up to 2.8m deep. These were aligned east-west and were located within the bawn area; only the ditch continued east of the curtain wall. Together they possibly represent the southern side of a massive stone-revetted earthen rampart which, from the associated finds, may date to the 12th century.

In category two of the pre-Norman phase, three structures forming a north-south row were situated beyond the line of the ditch towards the south side of the castle. Two were excavated almost completely and consisted of single-room sunken areas with a stone-lined entrance to the east. Both had slot trenches around the perimeter and rectangular postholes in the corners and at the entrances, providing evidence for timber frames to support planking. The respective floor levels did not include a hearth, suggesting that the structures may have been used for storage rather than as living accommodation. Only the stone-lined entrance and a small area of the floor level of the third were excavated fully, as most of the interior lay below the extant west bastion wall. The entrance originally consisted of two drystone walls widening towards the interior; the southern one was later partly rebuilt with mortared limestone. Incorporated into its western end was a stone jamb with a metal door pivot at the base. The back-filled deposits within all these features produced quantities of 12th-13th-century pottery, implying that they may have been in use up to the time the castle was constructed.

A long post-and-wattle fence was inserted into the partially infilled ditch along an east-west line. This was cut by the insertion of the curtain wall. It survived best on the east side and was connected to a separate post-and-wattle fence extending southwards. A later fence on the same east-west axis was discovered to the west of the curtain wall only. This also pre-dated the latter and was associated with clay deposits sealing the ditch fill.

The Norman occupation is represented within this excavated area by the remains of the east curtain wall. This was of mortared limestone and built in distinct sections beginning probably in the early 13th century. Section One extended south from the north-east corner tower for a distance of 13m and was c. 4m thick. This part of the wall did not continue beyond the line of the pre-Norman retaining wall which it met at right angles, proof that the earlier structure was utilised in the Norman defences for a limited duration.

The next two sections of the wall extended southwards across the ditch. Section Two was 7m in length and 2.6m wide, surviving to a maximum height of 2.8m. Section Three was a relatively poorly-built addition on a north-north-east to south-south-west alignment with a surviving length of 4.5m. The following 9.7m of the curtain wall has not survived. The circuit continued beyond this break, on the same alignment as Section Three, in the form of a severely truncated angled stretch which constituted the south-east corner of the pre 17th-century castle. Large pick-dressed limestone quoins seemed to denote a late medieval repair. There was no archaeological evidence for a corner tower.

With the completion of the curtain wall, the internal ground level was raised by means of a large-scale dumping of clay to a level corresponding closely to the modern surface.

The relatively weak nature of the south-east corner was rectified in 1611 with the addition of a diamond-shaped bastion, built by Josias Bodley. Its south and west walls still survive, to which can be added the remains of the eastern and northern ones as exposed by excavation. The east side was 16m long, the masonry surviving to a height of almost 4m. The north side was 8m in length and incorporated a sallyport of finely dressed limestone blocks.

A series of mines/countermines was found in the vicinity of the east curtain wall. Below section One, a collapsed clay-cut tunnel on the east side intruded upon a similar subsided passage extending from the west. Underneath the wall itself the mine survived to a maximum height of 1.8m. Further south, adjacent to the break in the line of the wall, were three timber-lined passages: a mine on the east side and two countermines to the west. When excavated they were found in a semi-collapsed state, but the wood was generally quite well preserved. All three were of broadly uniform construction, defined by opposing rows of stout uprights secured into short planks laid across the floor. The uprights were braced apart at the top with similar transverse beams which supported roofing timbers of varying dimensions. Behind the verticals, a lining of horizontal narrow planks retained the clay sides.

These mines can be dated with some precision as their construction is described in the Seige Diaries of 1642. From a statement in one of the accounts, a similar date may be ascribed to a ditch aligned north-south outside the curtain wall. This feature was followed for a distance of around 19m; it measured c. 2.5m in width by c. 1.3m in depth. Towards the north, the eastern edge of the ditch was cut into organic deposits which lay beyond the limit of the excavation. This black clay, together with similar organic material located at the base of the east bastion wall, provided the only indication to date for the presence of a moat contemporary with the castle during the medieval period.

c/o Planning Dept., Limerick Corporation, Limerick