Iron Age Hillforts

Hillforts were an important part of the Iron Age British landscape, especially in the west of Britain.

Iron Age Britons lived in organised tribal groups, ruled by chieftains. These groups would have changed and evolved throughout the Iron Age, and their early interactions seem to have been hostile, perhaps as tribal groups and boundaries settled in to place. This inter-tribal warfare was traditionally interpreted as the reason for the building of hillforts, as defensive areas where small communities across the landscape could muster and stand their ground when attacked.

But whilst some hillforts may have been defensive, others are sited on the sides of hills with poor defensive value, and these may simply have been communal gathering places or extended “homes” for the tribal elites. Some may even have simply been enclosures for domesticated animals such as cows.

Although the first had been built about 1500 BC, hillfort building peaked during the later Iron Age. There were thought to be around 2,000 Iron Age hillforts known in the British Isles, but in 2017, Oxford University published an online atlas of hillforts that doubles the number thought to exist. It has identified 4,147 hillforts in Britain and Ireland. There are 1,694 in Scotland; 1,224 in England (271 of which are in Northumberland); and 535 in Wales.

The construction of a hillfort was a massive engineering and logistical task. It has been estimated it would take 150 men about four months to construct an eight-acre enclosure with a single bank and ditch, using nothing more than antler picks, wooden spades and woven baskets to transport the soil.

To build a large hillfort, such as Danebury, Professor Barry Cunliffe estimated it would require two thousand timbers, each five metres long, to construct the ramparts together with the digging, carting and dumping of over 20,000 cubic metres of rubble. A smaller ten-acre hillfort such as Pen Dinas, Aberystwyth, may have required just over four and a half thousand trees from 188 acres of land to provide sufficient timber for vertical posts and tie beams. This represents an enormous consumption of resources, for only a medium-sized hillfort, and extensive woodland management over a wide area, with the builders having access to the timber produced and the labour required to fell the trees and provide haulage.

The method of construction is neatly illustrated at Ladle Hill, an unfinished hillfort near Newbury, Berkshire.

It isn’t known why it was abandoned but archaeologists are grateful, as it reveals how some hillforts might have been built. It appears that gangs of workers were used to deepen and widen an initial encircling shallow ditch in sections.

Wooden palisades were often constructed first. Around these, embankments, ditches and gateways – often with intricate interlocking entrances such as those at Maiden Castle – were designed to give the defenders maximum advantage against potential attackers. They seem to be most common in disputed areas, such as the Welsh Marches and Northumberland, where in the College Valley, every hilltop seems to be crowned by a hillfort, each visible from its neighbour.

By about 350 BC many hillforts went out of use and the remaining ones were reinforced. Why so many went out of use is not known. When Roman commander Vespasian was sent to ‘subdue’ southern Britain in 43 AD, he attacked a string of about 20 hillforts. The Celts’ main weapon of defence appears to have been simple slingshots and spears. At Danebury, a collection of more than 10,000 slingshot stones were discovered and the skeletons of severely injured bodies have been found buried in ditches there and at Maiden Castle.

After the invasion some hillforts, such as Hod Hill and Maiden Castle, were reused by the invaders as sites for forts or temples. Among the many things the Romans did for us was to construct roads, towns and an urban culture, and those Iron Age castles in the air were gradually abandoned to become the evocative, lonely monuments they are today.

A comprehensive survey of hillforts in Dorset can be found in this article, from Current Archaeology:

https://archaeology.co.uk/articles/features/iron-age-interior-design.htm