Ian W Thomson's doubts over whether the first-century battle of Mons Graupius ever took place might be at least partially assuaged through study of the place name (Letters, May 20).

The dearth of information about this encounter between the Romans under Agricola and the Caledonians under Calgacus has meant that for generations mysterious Mons Graupius has been tabbed "somewhere in north-east Scotland". But the notes by Tacitus bear a few tantalising clues – such as summa collium (the top of several hills) – to surmise that Bennachie by Inverurie, Aberdeenshire, may qualify as a location.

In 2002 Andrew Breeze, academic at the University of Navarre in Pamplona, put forward the idea (Proceedings of the Society of Antiquaries of Scotland, vol 132) that the words Mons Graupius relate to Welsh crib (ridge), and the actual shape of Bennachie provides confirmation of this etymology.

Mr Breeze examined the four-mile east-west ridge making up the peaks of Hermit Seat, Watch Craig, Oxen Craig and the familiar 1698-foot Mither Tap. Using the account of Tacitus and the Celtic language, he makes the observation that the silhouette of the four peaks resembles a comb for hair, or a coxcomb – a bird's crest.

He writes: "Cognates of Welsh crib 'comb' are known throughout the Celtic world. They are also used of ridges and summits ... Tacitus would have a Latin adjective ('Cripian') to go with the masculine mons."

The problem of how an original Cripius might be corrupted to Craupius, and by emendation to Grampian, he explains as: "We are dealing not with a Latin expression but a proto-Pictish one, which scribes would find outlandish and meaningless, and be particularly liable to copy incorrectly. The possibilities of accumulated error (when Tacitus wrote) and the 9th century (when our original was copied) need no underlining."

Thus Cripius might develop to Crapius, with a "u" thereafter intruding to Craupius, followed by Graupius. "This 'u' became 'm' in the 15th-century printed edition of Agricola, giving the 'Grampian' of modern maps, television and local government."

Such letter substitution is not unusual: the island we call Iona was once Ioua, the island of yew (tree).

If Mr Breeze is correct, then not only did the battle of Mons Graupius take place but, by its etymology, Mons Cripius (Cripian Mountain) would rule out competing battle sites such as Raedykes in Kincardineshire, Duncrub near Dunning in Perthshire and Sillyearn at the Pass of Grange in Banffshire.

Gordon Casely,

Westerton Cottage,

Crathes, Kincardineshire.

As someone with more than a little interest in our Roman past, I found the article concerning Mons Graupius quite fascinating ("Archaeologist claims to have located site of Roman battle", The Herald, May 18).

Doubts and theories concerning the battle between Agricola's Roman army and the Caledonii have been around for some time and no doubt it will take considerable further study and digs to put more meat on the bones of Mike Haseler's theories.

A detailed study by Roman Scotland produced 29 sites as contenders for Mons Graupius, with the top 10 all in Perthshire/Strathearn. The key to verifying claimants' credentials probably lies in the writings of the poet and historian Tacitus who was also Agricola's son-in-law.

Despite some clearly imaginative accounts of Calgacus the Caledonii leader, his descriptions of the post-battle scenario are quite illuminating. Tacitus tells us that following the battle, Agricola withdrew to make contact with the Roman supply fleet as it was too late in the year for operations on land to be extended, a possible indication that events did not take place as far north as Moray.

During this episode Agricola took hostages from a people known as the Boresti, a tribe who probably inhabited parts of Fife. The Roman Scotland conclusion was that the battle had most likely taken place at Dunning near Auchterarder.

The closest rival to this was the Gask Ridge between Crieff and Perth. Extensive archaeological research over the past decade has confirmed the Gask Ridge is the oldest Roman frontier in Europe pre-dating the Hadrian and Antonine walls. There has been much conjecture concerning Mons Graupius. It is clear there is indeed much more to be revealed.

Colin Mayall,

5a East High Street,

Crieff.

Ian Thomson's letter (May 20) doubting the existence of Mons Graupius is interesting but factually inaccurate.

Tacitus had no need to invent a battle and the reason he invented a speech by Calagacus (which means swordsman) was because he was an old-fashioned Republican who did not agree with the Empire. Had he made such views known publicly then a letter from the Emperor would have informed him that he had 24 hours to put his affairs in order and kill himself. Therefore he put his criticism into the mouth of a barbarian, who admittedly may have also not existed as swordsman (calagacus) is a very general term.

The Romans were great archivists and there is no doubt the reports by Agricola which he would have regularly sent back to the Emperor would have contained information which could be checked by Agricola's readers.

The Romans were also familiar with the idea of a general making a speech to his troops on the eve of battle, so putting one into the mouth of a barbarian would have been accepted by them. Thus did Agricola have a means of setting out what he thought about the Roman Empire without rubbing the Emperor up the wrong way.

The Romans also had a habit of "bigging up" their opponents, because that made any victory for them all the more fabulous. But Mons Graupius being invented? No, because whether the numbers involved were accurate or not, or whether the name of the Pictish leader was accurate or not, the fact that there was a battle can be taken as fact. The archives, which have long gone for us to consult, would have been easily consulted by anyone at the time.

The recall of Agricola when he was ready to take over the whole of Scotland and then move to Ireland was a piece of politics.

Such a successful general with four legions under his command (in modern equivalent terms about half of Nato) and an entire archipelago behind him, could have become a serious threat to the Imperial throne.

Alex Flett,

Lochfergus House,

Kirkcudbright.