Mons Graupius Identified
Factor 3. Interpretation: A Practical Analysis
Having reviewed Tacitus’s account in "The Agricola" and the dispositions of bona-fida Flavian period marching camps in central and northern Scotland we shall now turn our attention to interpreting this information in a manner that we can then relate the various contending sites against.
The Size of the Opposing Armies.
The size of the Caledonian host mentioned by Tacitus; 30,000, seems excessive to many modern commentators, and it certainly is a very round figure for what at the time can only have been an estimation of numbers of the Caledonian host marshalled at the foot and on the slopes of Mons Graupius.
Clearly not all tribes in the north were involved or Agricola would subsequently have had no need to send his admiral - with additional troops - to "spread the terror of Rome.... before him" as due to the “lateness of the season” he had been unable to "extend (land) operations over a wider area" (Agricola Ch. 38).
General Wade’s military assessment of the strength of the Highland clans in the Jacobite period (early to mid 18th C AD) estimated a fighting strength of 33,000 men of fighting age. This estimate was restricted to manpower within the highland zone.
The forces opposing Agricola - based on the statements above by Tacitus in Chapter 38 - clearly did not consist of all the most northerly tribes. The Romans however - unlike the Jacobite period assessment of highland strength - on the other hand also faced the manpower of the organised and numerous "lowland tribes" such as the Venicones and Vacomagi - including their many smaller satellite tribes of which we no longer have any knowledge - as well as the strength of the scattered septs and embryonic “clans” of the highland zone.
In medieval Scotland, in times of major national duress- normally invasion and war with England - a general call up was expected to gather in all able bodied males between 16 and 60 years old.
That a similar if not wider aged call to arms would have applied in the late first century AD in the face of the exceptional level of threat posed by the massive invading Roman forces need not be doubted.
30,000 men, boys and greybeards, called out in defence of hearth and home, kith and kin and the tribal homeland – while a generalised number - may then not be too far off the mark.
The best comparator we have however in making this assessment is not the number of Jacobite clansmen of the 18th C AD, but very tellingly the numbers of troops the Romans felt necessary to bring to bear to deal with the tribes of Scotland.
The size of the Roman Army that Agricola brought north in 79 AD can best be gauged by the marching camp at Pathhead in the Lothians. This characteristically square Flavian marching camp is capable of accommodating over 30,500 men.
It clearly shows Agricola was prepared to ensure the Votadini were suitably cowed and left in no doubt that the best course of action would be to submit or more probably fully comply with the terms of any treaty hammered out in advance of Agricola’s advance into Scotland.
At this stage the Roman garrison of Britain comprised four legions (totaling around 22,000 legionaries) and this is likely to have been exceeded by or at the very least matched by a similar number of auxiliaries.
Marching north- at least at first till the tribes reaction could be gauged - with just under three quarters of the entire Roman garrison of Britannia may seem a bit over confident given that large tracts of northern England and Wales had only recently been brought under the Imperial heel. However the historical record makes it clear that those areas would fail to prove any further trial to Rome while Agricola would have been fully aware of the martial reputation of the northern tribes.
By the time Agricola advanced north of the Forth-Clyde line in 82 AD - either following Imperial instruction or alternatively actively pursuing glory- he had been forced to send the equivalent of a legion and probably a matching number of auxiliaries to assist the Emperor Domitian’s problematic Chatti campaign on the continent.
(For further discussion of Agricola’s 82 AD campaign see the addendum).
In 83 AD these troops were still on the continent. Casualties- both legionary and auxiliary- incurred in the previous years campaigning in Scotland coupled with an undoubted difficulty securing replacements (Imperial prerogative would ensure that drafts of new recruits would be directed to the Chatti theatre of operations) increased Agricola’s manpower problem to the stage we are told he took the unusual step of using in this campaign auxiliaries recruited from tribes within Britain itself. At this time non citizen troops normally served outwith their own lands).
Antiquarians, southern historians and others not prepared to give the matter much thought have tended to blithely attribute a force of 20,000 men to Agricola in 83 AD. This nice round figure was attractive -it appears- for no better reason than it is substantially less than the Caledonians at 30,000, a figure which ironically the same historians rarely find the need to question.
It should be remembered that partisan anglo-centric interest was and to an extent still is at stake through comparison; only 23 years earlier Suetonius Paulinus with only 10,000 troops had thrashed Boudicca’s rolling tribal behemoth of over 230,000 (including non combatants) in southern England slaying 80,000 in the process.
This prevailing lightweight level of analysis of Agricola’s strength is something we can easily improve on.
We refer to Tacitus who gives us some useful figures to start working with. Clearly Tacitus account is designed to allow the reader to imagine a disparity in numbers between the opposing forces, and one that would of course reflect on Agricola in glowing terms. While not actually laying himself open to the charge of falsifying numbers, he does however decide to be economical with information that would otherwise give a more balanced reading of the situation on that fateful morning.
His deployed battleline of 8,000 auxiliary infantry was flanked by 3,000 cavalry split (we presume equally) between the wings. The four reserve cavalry squadrons that he unleashed with cataclysmic effect, possibly his own bodyguard can be equated to a further 2,000. This gives a combined auxiliary total of 13,000 troops.
It was standard Roman practice on campaign to match the numbers of legionary citizen troops to that of non - citizen auxiliary soldiers. 13,000 legionaries- in the event never employed in the battle - would give Agricola circa 26,000 troops at his disposal on the field on the day at Mons Graupius.
This is substantially smaller than his total field force in 79 AD but still stronger in terms of the percentage of garrison in Britain employed due to Domitian’s drain of manpower early in 82 AD. Hence Agricola’s noteworthy decision to employ locally recruited auxiliaries.
A figure of 13,000 legionaries should not be dismissed out of hand as a convenient round figure.
Out of the four legions in Britain Agricola still had available what amounted to the manpower of three full strength legions. At full strength this would muster circa 16,500 troops.
Each of the four under strength legions - it is unthinkable that with the prospect of a showdown looming with the Caledonians in the campaigning season of 83 AD that Agricola would not have brought all four north with him - will have left only a skeleton force at their legionary depots in the south, probably a cohort apiece (around 500 men).
This reduces the figure available for field duty by at least 2,000 to circa 14,500 men.
We then have to factor in casualties sustained through the preceding years campaigning (82 AD in particular) as well as losses through sickness (always more difficult to prevent in long periods on campaign than in barracks) and injuries and the figure of 13,000 legionaries available for campaigning looks entirely plausible.
In this light, a Roman force of around 26,000 men does not appear quite so extraordinarily outnumbered by 30,000 Caledonians as Tacitus would allow us to believe.
His decision to “omit” quantifying the legionary element of the force would have been a slip excusable in ancient times by those experienced enough in military matters to do the arithmetic for themselves, but would look mightily impressive to the masses of Rome who would have been unlikely to care enough to question or take the time to work out how many legionaries were actually there, principally as in the event they were not actually needed.
NEXT PAGE: What space would Agricola’s army require on the field?
©2009 Roman Scotland. All Rights Reserved
First Published February 2009
