Slack Roman Fort, a castellum (fort) in the Roman province of Britannia may have been the Cambodunum mentioned as a station on this route in the Antonine Itinerary. Its remains are buried near the hamlet of Slack near Outlane to the west of Huddersfield in West Yorkshire, England. Its site is a scheduled monument. The ruins of the fort, which lay alongside the Pennine section of the Roman road from Deva Victrix (Chester) to Eboracum (York), are no longer visible; part of the site lies beneath the M62 motorway.
Archaeological digs indicate the fort was constructed of turf and wood to defend the Roman road in the time of Agricola in 79 AD. Outside the fort walls was a stone bath house which was extended between 104 and 120 AD. An adjacent vicus, or small civillian settlement of wooden huts, remained in occupation after the fort was abandoned.
The fort occupied an elevated site on sloping ground formed by the valley of the Longwood Brook to the west and south, with the vicus to its north and east. The M62 motorway was built over the course of the Roman road and part of the vicus. The fort is sheltered by a hill rising to 1200 feet (366 m) above sea level, about four miles (6 km) from Huddersfield. Observation posts on the surrounding hills commanded views towards Blackstone Edge, Standedge, Huddersfield and the Stainland Valley in the Halifax direction.
Roman forts in Britain were constructed between the mid-1st and mid-2nd centuries AD. Typically they were rectangular in plan with rounded corners, defined by turf ramparts and an outer ditch. The forts had a headquarters building (principia) to the centre, a house for the commander (praetorium), one or more granaries and rows of barracks. The first forts were built from timber, but stone was used from the 2nd century AD. The forts often had a bath house outside the ramparts. A civilian settlement (vicus) often grew up around a fort.
Slack Roman fort has been identified as Cambodunum, a name recorded in the Antonine Itineraries. Adjacent to the Roman road linking Deva Victrix (Chester) and Eboracum (York), it was built in about 80 AD. The garrison was probably reduced in about 122–125 AD, and it was abandoned some time between around 140 and 160 AD. The vicus may have been occupied into the 3rd or 4th century.
The fort was mentioned in J. Whitaker’s History of Manchester (1771). Part of the bath house was first excavated in 1824 when a section of the hypocaust was removed. The bath house was again investigated by the Huddersfield Archaeological and Topographical Association in 1865. Its members uncovered a stone-built structure with at least one unheated and four heated rooms. The society uncovered the remains of a residence measuring 60 feet by 68 feet with a courtyard. Nearby was a cremation site and on the slope 80 yards (73 m) below the house are the remains of a hypocaust for the hot-air bath. Also found nearby were a British stone axe, pottery, part of a brooch and a quantity of galena, (lead ore). On another part of the site are the remains of a cold bath comprised of a slab of concrete 13 feet 6 inches long by 6 feet 3 inches wide and a red tiled floor. Copper or bronze coins from the reigns of Vespasian and Nerva, an earthenware jar and a tile stamped “COH IIII BRE” were also uncovered.
Excavations between 1913 and 1915 and 1958 to 1963 uncovered the fort’s ramparts and the foundations of its gateways and corner towers. The ramparts, constructed of turves on a stone footing, surrounded an area 356 feet square. They were surrounded by a ditch, in some parts a double ditch when the fort was built. Inside the ramparts the outlines of several wooden buildings including the military headquarters and barrack blocks. were uncovered. The excavations aso uncovered another phase of development about 20 years later that added two granaries roofed with tiles stamped COHIIIIBRE, the mark of the 4th cohort of Breuci who operated a tilery in the nearby Grimescar Valley. A phase of building in stone began in the early AD 120s. Excavations in 1958–63 investigated the area now considered to be the vicus.
Rescue excavations in 1968–69, before the construction of the M62 motorway, identified the Roman road and at least two phases of timber buildings fronting onto it. Pottery finds were originally dated to 80–140 AD, but have subsequently been dated to well into the 3rd century.
The West Yorkshire Archaeology Service excavated the vicus in 1995 identifing ditches, wall lines, cobbled and paved surfaces. In 2006 Bradford University’s geophysical surveys suggested that the vicus was more extensive than thought to the northeast, where data suggested a possible kiln or furnace site. The survey identified the possible remains of the praetorium in the unexcavated southwestern part of the fort. Between 2007 and 2010 the Huddersfield and District Archaeological Society’s excavations identified parts of a stone-built and timber-lined aqueduct that was radio-carbon dated to 210–340 AD. Other metal, ceramic and glass finds were dated to the 1st to early 4th centuries.
The Tolson Museum in Huddersfield has a collection of artefacts including the reconstructed Grade II listed remains of the hypocaust, comprising the rubble columns and tiled floor, that were moved to Ravensknowle Park. The Roman fort with its defended vicus survives as buried archaeological deposits and low earthworks. Its site is a scheduled monument.