2004:1544 - FORTHILL, SLIGO, Sligo

Excavations were undertaken in advance of the construction of a new access road from the Connaughton Road across the line of the 17th-century town defences, erected by Jacobite forces in the autumn of 1689, which extend westward from an earthen star-shaped fort known locally as the 'Green Fort'. Historical evidence and trial-trenching by James Eogan in 2000 (Excavations 2000, No. 902, 00E0395) suggested that these defences comprised ditches and earthen banks.

A low clay bank ran east-west across the site, with a drystone wall set along its southern side and an associated subsoil-cut ditch about 1.5m to the north. The linear ditch ran east-west across the site and was up to 1.2m wide. It was U-shaped in profile, although its northern side was noticeably steeper than the southern, and it survived to a depth of about 0.55m near the eastern limit of the excavation area. Near the western limit of the site it survived to a depth of 0.18m. It was filled with various charcoal-flecked silty clays and small stones.

A metal button and a small quantity of oyster shells were recovered during the excavation of the basal fill of the ditch. The metal button was made from a copper alloy and retained some small patches of tinning, although there was no evidence of decoration (Susannah Kelly, pers. comm.).

The material excavated during the initial cutting of the ditch appears to have been used to construct the clay bank to the south. In the eastern part of the excavation area, where both the bank and ditch seem to have survived intact, the clay bank was located about 1.4m to the south of the ditch and closely followed its course. To the west, the bank was up to 1.8m from the southern edge of the ditch. The clay bank was c. 1.65m wide and up to 0.55m in height with a shallow, rounded profile. It consisted of various layers of redeposited clay subsoil, deposited in layers 0.2m thick.

A shallow foundation slot had been excavated through subsoil to the immediate south of the clay bank. It followed the line of the bank and was 0.5m wide (north-south) and up to 0.2m deep. Its sides and base were irregular in form. This slot served as a foundation trench for a drystone wall that butted against the southern side of the bank. However, it was not possible to ascertain whether the cutting of the slot and subsequent construction of the wall were a component part of the construction of the bank or a later addition, perhaps associated with the reuse of the defences as a field boundary.

The wall consisted of uncoursed blocks of rough limestone and survived to a height of 0.5m and width of 0.5m (north-south). The stone blocks averaged 0.2m by 0.1m by 0.1m in size. No signs of mortar were apparent. Two red clay bricks were recovered from the basal layer of stonework.

A linear section of gully was identified c. 1.75m to the north of the ditch and this ran east-west for a distance of 2.67m. It was 0.4m wide, up to 0.09m deep and had very slightly rounded terminals, steeply sloping sides and a flat base. It was filled with a charcoal-flecked, compact, mid-brown clay that contained a moderate amount of small sub-angular stones.

The paucity of artefactual and radiocarbon dating evidence means that it is not possible to ascribe a date to the earthwork with any real certainty. Moreover, it was not possible to satisfactorily determine the chronological relationship of the drystone wall/possible revetment with the bank during excavation. However, the evidence from the physical remains, combined with the historical maps and documentary evidence, appear to corroborate the historical documentary evidence for Luttrell's 1689 retrenchment of Sligo's defences and it seems highly likely that the features identified within the excavation area were part of these works.