The location of the battle of Mons Graupius

Around 80AD, the governor of the Roman province of Britannia, Agricola, attempted to conquer Caledonia. After subjugating the Celtic tribes of Wales and the Brigantes and other tribes to the north of Britannia, he turned his attention to Caledonia. The Caledonian tribes were based north of the Forth and the Clyde. The Roman historian Tacitus, who was the son in law of Agricola, provided an account of Agricola's campaigns in Caledonia. According to Tacitus, the Romans and Caledonians fought a major battle at a place called Mons Graupius. The battle was a decisive victory for the Romans. The Romans lost around 350 men and the Caledonians lost around 10,000 men. However, Tacitus may have greatly exaggerated the number of casualties. 
By the third year, Agricola had conquered the tribes as far north as the Firth of Tay. He also built forts at places like Ardoch, Strageath and Bertha. In the fourth year, he built forts between the Forth and the Clyde along the Antonine line. In the fifth year, Agricola campaigned in the south west of Scotland. By the sixth year, Agricola invades Caledonia. He sends the fleet up the east coast to explore the harbours. However, the Roman army is harassed by the Caledonian tribes who wage a guerrilla war. During the sixth year, the Caledonians attacked the 9th legion in one of the forts. The 9th legion were rescued by Agricola and the Roman army at the last minute. This may have taken place at Ardoch. The Roman fort at Ardoch has around six to seven outer ditches. Most Roman forts in Scotland only have around two to three outer ditches. This suggests that Ardoch was attacked by the Caledonians, with the Romans building additional ditches following these events. In the seventh year, Agricola continues the campaign in Caledonia. He sends the fleet up the coast to harass the enemy. The Romans march to Mons Graupius where they find the Caledonian army. According to Tacitus, the battle of Mons Graupius takes place in the far north of Caledonia by the coast. In the speech of Calgacus, the leader of the Caledonians, he says "there are no tribes beyond us, nothing but waves and rocks ..." However, we should consider that Tacitus was writing for a Roman audience. The location of Mons Graupius is unknown. This article will focus on five proposed locations - Dunning in Strathearn to the south, Moncrieffe hill close to Perth, Blairgowrie in Perthshire, the Caterthuns in Strathmore and Bennachie in Aberdeenshire.

A map of the Roman marching camps in Strathmore. The 63 acre marching camps head to Keithock before descending to the south of the Sidlaws.

Dunning is located just to the south of the River Earn and to the north of the Ochil hills. The idea that the battle took place at Dunning is based on a placename nearby called Duncrub. This is Gaelic for the fort of the ridge. The name Graupius is derived from the word crub. There is also a Roman marching camp at Dunning of around 115 acres. This would have had space for around 30,000 troops. According to Tacitus, Agricola's army had around 8,000 auxiliaries, 3,000 cavalry and a couple of legions of around 5,000 men each. However, the location of Dunning just doesn't make any sense. The Caledonians would have been positioned on the Ochil hills to the south of the Roman army. Furthermore, Strathearn was not the territory of the Caledonii. The Caledonii were based in Dunkeld and Atholl to the north. It's more likely that the Romans marched through Dunning on their way to the Firth of Tay in the third year of campaigning.

Moncrieffe hill is located just to the south of Perth and the River Tay. The River Earn runs just to the south where it joins the River Tay. Just to the south of the River Earn, there's a Roman marching camp at Carey of around 115 acres. This location doesn't make any sense either. The Caledonians would have been positioned on Moncrieffe hill. The hill is very steep and the River Tay would have prevented the Caledonian retreat. Furthermore, Moncrieffe hill would have been defended by the River Earn, so it would have been difficult for the Roman army to approach the hill. Some historians have also suggested that the name Moncrieffe is derived from Moncrub. However, Moncrieffe is Gaelic for the hill of the tree. Again, the Romans may have marched to Carey and the Firth of Tay in the third year of campaigning.

Blairgowrie and the Caterthuns are my favoured locations. Blairgowrie is located just to the south of the highlands on the southern boundary of Atholl, the lands of the Caledonii. Dunkeld, which may have been the capital of the Caledonii, is located a few miles to the west. Furthermore, the Roman legionary fortress of Inchtuthil, which dates to the time of Agricola, is located just to the south west. The hill of Blair overlooks a plain which matches the description of Tacitus of the battlefield. In the 1700s and 1800s, Blairgowrie was a popular location amongst historians and antiquarians for the battle of Mons Graupius. If the battle took place at Blairgowrie, the Romans would have camped at Inchtuthil. However, there is no obvious marching camp at Inchtuthil. There's only the legionary fortress of around 50 acres and a temporary camp for the labourers of around 50 acres.

The hill of Blair.

The Caterthuns are located further up Strathmore, just to the south of the highlands. They're located at the boundary of Angus and the Mearns. The Caterthuns are two ancient hillforts which overlook a pass into the highlands. The North Sea is a few miles to the south east. On the north side of the bay of Montrose, there's a small Roman naval camp, which dates to the time of Agricola. At Stracathro, there's the northernmost Roman fort in Scotland, which also dates to the time of Agricola. Furthermore, there's a Roman marching camp at Keithock of around 63 acres, just to the south east of the Caterthuns. This is part of a series of 63 acre marching camps which run from Ardoch to Bertha, up Strathmore to Keithock, before descending to the south of the Sidlaws. They then seem to the cross the River Tay into Fife. This matches the description of Tacitus that the Romans withdrew to the territory of the Boresti where they took hostages after the battle of Mons Graupius. Many historians have suggested that the Boresti were based in Fife. Historians and archaeologists have suggested that the 63 acre marching camps belong to the campaigns of Severus around 210AD. However, there is no dating evidence for this. They have also suggested that the 130 acre marching camps in Strathmore belong to the campaigns of Severus. If this is the case, how did Agricola's army march through Strathmore? There are no other significant marching camps in Strathmore. There's only a 40 acre marching camp at Stracathro, which would have had space for a single legion. Whilst the 130 acre marching camps probably belong to the campaigns of Severus, the 63 acre marching camps may belong to the campaigns of Agricola. The 63 acre marching camps would have had space for around 17,000 troops. At Ardoch, there's a 130 acre marching camp which overlaps a 63 acre marching camp. This suggests that the 63 acre marching camp is the earlier camp. How much earlier is unclear. The Welsh naturalist and antiquarian, Thomas Pennant, visited the Caterthuns in 1772. He suggested that the battle of Mons Graupius was fought at the Caterthuns.

The Caterthun hillforts.
Photo by Kieran Baxter.

A map of the Caterthuns and Keithock marching camp.
William Roy military survey, 1747-55

Bennachie is a hill in Aberdeenshire. On the summit, there's a hillfort called Mither Tap. To the north east, there's a Roman marching camp at Durno of around 140 acres. This would have had space for around 40,000 troops. The design and layout of this marching camp is very similar to the 130 acre camp at Ardoch. As such, it probably belongs to the campaigns of Severus. Around 210AD, the Roman emperor Severus invaded Caledonia with a huge army of around 40,000 men. He supposedly marched to the far north of Caledonia and negotiated terms with the northern tribes. The location of the marching camp at Durno suggests that the Romans simply marched by Bennachie as opposed to positioning themselves for a battle. Furthermore, Bennachie is far from the lands of the Caledonii.

Overall, I would say that the Caterthuns are the most likely location for the battle of Mons Graupius. The Caterthuns are located in Angus and the Mearns, which formed the ancient Pictish province of Circinn. The historical records refer to Magh Circinn, the plains of Circinn. The Caterthuns are also located on the 'mounth' of the Grampians. The name Grampians is derived from Graupius. However, there are a couple of issues with this theory. Firstly, one of the marching camps in Aberdeenshire at Kintore was supposedly dated to the campaigns of Agricola and Severus. The marching camp is around 120 acres. However, I would question the reliability of the radiocarbon dates. Secondly, the marching camp at Keithock close to the Caterthuns is part of a series of 63 acre marching camps. The size of all of these marching camps are similar. If these were Agricola's camps, it suggests that the Romans didn't have many casualties at the battle of Mons Graupius. Of course, Tacitus says that only around 350 Romans were killed at the battle. Therefore, the marching camps wouldn't have changed significantly in size. However, I would have thought that the Romans would have suffered more casualties at the battle. The size of the Caledonian army was supposedly 30,000 men. This was a sizeable force which should have inflicted more casualties on the Romans.
So what actually happened? Did Agricola simply march up to the Caterthuns and negotiate terms with the Caledonians before withdrawing to the territory of the Boresti? Or did the battle actually take place and Tacitus' account was truthful? If archaeologists could date the 63 acre marching camps, it would bring us closer to locating the battlefield of Mons Graupius.