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Calling all armchair generals! Boudica's Last Stand.
Renatus wrote, "how does one calculate the course and flow of a minor river 2000 years ago?"

The following passages outline the method I use. The passages come from my earlier essays. I have not cut-n-pasted all the relevant text. Use the links to read more - especially the second link.

I think that will do, don't you?



The following is taken from

Finding_the_site_of_Boudicas_last_battle_Roman_logistics_empowered_the_sword._Steve_Kaye._2013

In outline, the catchment water balance methodology was used in this study for the whole of Britain (Figure 5). This involves calculating the mean flow in rivers by use of rainfall, potential evapotranspiration losses, and catchment characteristics such as area sizes, topographic and geological descriptors and models of the river systems. All these investigations, and other supporting statistical and mathematical calculations, were conducted within SAGA (System for Automated Geoscientific Analyses), a GIS and calculation engine, that contains the key hydrological modules used in this study.

We are interested in river flows in the summer of 60/61AD, especially those within and on the margins of the chalk and limestone uplands of southern Britain. Therefore, the values of the Q95, for the period 1961-2006, have been computed for August and for naturalised catchment and river systems. Essentially these Q95 values - at the height of summer, when rainfall, surface runoff, aquifer discharge and consequently river flows are at a minimum, tells us where these large armies could march and give battle.

It should be made clear that the calculation of low flows is fraught with difficulties and uncertainties, especially when examining flows in the ranges required for this study. The results are imperfect, have unknown error ranges, but are generally representative of the flows the protagonists would have experienced in marching across southern Britain.

It is in part due to these hydrological uncertainties that the numbers of humans and animals was kept low, and the water requirement for humans lowered to 9 litres/man/day rather than use the larger figure from the investigations of the US Army.

The base data used in the aforementioned calculations were:

Shuttle Radar Topography Mission (SRTM), Jarvis A., H.I. Reuter, A. Nelson, E. Guevara, 2006,

Hole-filled seamless SRTM data V3, International Centre for Tropical Agriculture (CIAT), available

from http://srtm.csi.cgiar.org

Rainfall, long term average per month for years 1961-2006 from the Meteorological Office -

http://www.metoffice.gov.uk/climatechang...nthly.html

Evapotranspiration figures from MODIS 16; a NASA/EOS project to estimate global terrestrial

evapotranspiration from the earth land surface by using satellite remote sensing data.

http://www.ntsg.umt.edu/project/MOD16/


Main references to the method are:

Gustard, A., Bullock, A. and Dixon, J, (1992), Report No. 108. Low flow estimation in the United

Kingdom, Institute of Hydrology (NERC).

Gustard, A., Marshall, D., and Sutcliffe, M., (1987), Report No. 101. Low flow estimation in

Scotland, Institute of Hydrology (NERC).


The following is taken from

The_Roman_invasion_of_Britain_43_AD_riverine_wading_and_tidal_studies_as_a_means_of_limiting_the_possible_locations_of_the_invasion-ground_and_the_two

In outline, the task was to determine by calculation the natural channels created by the rivers of SE England in 43 AD and then fill these with the discharge for July 43 AD. This exercise derived discharge rates, depths, widths and velocities for all rivers at the time of the two-day river battle.

The mean annual discharge (a.k.a. average annual discharge) can be used to calculate the bankfull state of a river. The bankfull discharge is that which fills the main channel of a river to capacity; any additional discharge causes over-banking and the flooding of adjacent land. It is generally accepted by most hydrological agencies that the dominant or channel-forming discharge for a dynamically stable channel approximates to the bankfull discharge, i.e. that which determines the gross parameters of the channel, e.g. depth, width, meander sinuosity etc..

Hence, in this study the mean annual discharge (Qannual) for the years 1961-2011 was calculated using the catchment water balance method (Gustard et al, 1992) augmented by calculations of the base flow index (BFI - see definition at http://www.ceh.ac.uk/data/nrfa/data/derived_flow.html) to derive aquifer discharge to rivers. Mean annual precipitation data were taken from the UK Climate Projections study (UKCP09) and mean annual evapotranspiration data from Trabucco and Zomer (2009) for the years 1950-2000.

For this study the derived Qannual value at Teddington on the Thames was 76 m3/s, while at the same location the long-term (1883-1985) measured value is 78.2 m3/s (Beran and Field, 1988). The latter results from point measurements made at Teddington; the former the result of a very large number of individual calculations throughout the drainage basin all accumulating at Teddington: the correspondence between 78 and 76 m3/s suggested the results of the hydrology calculations were plausible.

The bankfull variables depth, width, velocity and discharge for a half-hexagon channel shape were derived in the following manner:

Bankfull depth - derived from a power function of catchment area, (following the findings instigated by Leopold and Maddock, 1953).

Bankfull width - estimation of river widths in Google Earth at 61 points in SE England. Allowance was made for human interference, e.g. averaging the width up and downstream of weirs. These 61 values were regressed against Qannual to give, , R2 of 76.49%. This equation was used to derive bankfull widths for all rivers in SE England.

Bankfull velocity - derived from the Manning velocity formula (a standard hydrological method), where v is the bankfull velocity; k is 1.0 (metric conversion number); n is a roughness coefficient set to 0.07 for rivers of width less than 30 m or 0.065 for greater, e.g. the Thames; R is the hydraulic radius and S is the slope of the channel. The values for n were relatively high compared to values assigned to the same modern-era rivers; this reflected the wider and shallower nature of the ancient rivers and the greater amounts of vegetation bordering and within the river.

Bankfull discharge - derived from the formula, discharge = width*depth*velocity
Reply
Quote:We are interested in river flows in the summer of 60/61AD... Therefore, the values of the Q95, for the period 1961-2006, have been computed for August... Essentially these Q95 values... tells us where these large armies could march and give battle.

Have you found any pre-19th century statistics? I'm possibly missing something here, but bearing in mind the enormous changes that have taken place since the industrial revolution, can values from 1961-2006 be representative of the situation 2000 years ago?

Industrial use of water and population growth have greatly depleted water levels in all rivers surrounding London (the Ver was possibly navigable for sea-going vessels as far as St Albans in Roman times - now it's a small stream) - might there be some way to account for that depletion in statistical analyses?
Nathan Ross
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I don't know I leave you guys alone for a few days and it all kicks off......play nice chaps, it's only a game.

1 The Wash, I'm still convinced this is an underplayed impediment to the Iceni manoeuvres. The higher sea level only compounds the issue of impassability. Holme Post demonstrates how quickly and dramatically these levels can change;
http://en.wikipedia.org/wiki/Holme,_Cambridgeshire
The Wash population probably jumped significantly in late 61AD with Paulinus' reprisals, but this population was probably sedentary and reliant on water transport, hence I still contend that any advancing horde would probably have passed to the South of the area.

2 My bias, I'm completely open about this, Steve's work is a fantastic think piece and for Church Stowe (CS) to land at 47 out of 2700 candidates puts it in the top 2% so I see that as a distinct validation of the hypothysis that CS might be a good candidate site. My focus on CS is just a method to test the necessarliy subjective assumptions of Steves paper. This paper makes me think differently at a strategic level and the process of site justification is throwing up new observations which I think are of value. They help me test/build my case hopefully they will help the same process for other sites.

3 Distance from known position of the protagonists. This seems a factor so obvious it should be probably the key determinant of the filtering process. Any site near the known Roman route and the known Iceni postions should be weighted so massively positively to make any candidate outside this zone a rank outsider. Steves candidate list has popped up with lead candidates so far West and South that in my book they are just not credible, so I am mentally striking them out. How one accounts for this in terms of weighting I'm not sure but it seems such an obvious factor. So many of the candidates demand an unfeasibly long march in by the Iceni and such a long retreat form the enemy by Paulinus that surely they would have warrented mention in the texts, or the late arrival of Legio II.

4 Sausages, 3 diagrams illustrating the point,

4a Roman route on Watling Street and MAYBE West of London with a zone of deviation;

[attachment=11942]sausagesroman.jpg[/attachment]

4b Iceni routes out of East Anglia, northern option to attack Roman route march, Southern, Thames Valley route because that is the only way to justify distant sites;

[attachment=11943]sausagesbrit.jpg[/attachment]

4c Sausage on Sausage, the intersections should be the best candidate sites, yes the northern route seems to land on Church Stowe and the bifurcation happens to negate Dunstable, funny that, bring it on Ross you don't scare me.....

[attachment=11944]sausagescomposite.jpg[/attachment]

and here is a clear warning that an undue obsession with the West will do you no good;

www.youtube.com/watch?v=r5adzgP8vtE
:razz:


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Quote:Sausage on Sausage, the intersections should be the best candidate sites

Surely one of the most bizarre phrases ever to appear on here - well done! :-)

I quite like your sausages, but I don't understand why one of them is bending up to the north. Why would the Iceni go this way? (except to get to Church Stowe...). With the Wash now a major obstacle, it seems all the more unlikely that Boudica would take her big disparate tribal horde all the way into the midlands. What's the objective?
Nathan Ross
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Quote:With the Wash now a major obstacle, it seems all the more unlikely that Boudica would take her big disparate tribal horde all the way into the midlands. What's the objective?
My thoughts exactly. What has the Wash got to do with any of this? We know that the rebels went south to the centres of Romanisation - Colchester, London and St Albans - and that Suetonius went to London. They could not have got much further from the Wash, if they had tried.
Michael King Macdona

And do as adversaries do in law, -
Strive mightily, but eat and drink as friends.
(The Taming of the Shrew: Act 1, Scene 2)
Reply
Why would the Iceni go this way?
because they are looking for a fight. They know the Romans are coming down Watling Street or assembling around the Street so they are going to get them. We could go for a direct westward move across the Wash as Steve hints it may be passable, but I'd suggest they are off for a hunting expedition up Watling Street to finish off the Romans, last seen returning from a recce to London. (recce implies far less elan and more routine than dash in my dictionary) also the move to hit a Roman position on Watling Street, need not have come up the road itself, maybe the Ouse or Nene vallies instead, Roman Roads are massively over rated by Romanists.

We know that the rebels went south to the centres of Romanisation - Colchester, London and St Albans
We "know" they went to Colchester, we "know" some of them went to London and St Albans, we don't know if this was from the the North or East in the case of St Albans, you are overtly over egging the knowns with this, a little more discipline please, but I'm pretty sure I'm repeating recent stuff here.


Let me try and help you with the Wash stuff, it's not too deep and I'm sorry you are finding it impenetrable...... :whistle:
The Wash was an impediment to the Iceni movement, yes? (nod here)
It was big and wet and between Iceniland and where we know the Romans to have been during their advance South, yes? (nod here)
OK that means we can speculate that whether, in a first advance immediately post Colchester, or a second later advance, the Iceni and/or Trinovanti left what is effectively an East Anglian Peninsula somewhere between Great Chesterford and the Thames, thus delimiting their movement to a particular front, ok? Idea Idea Idea (did you get that one? if so please nod again)

"Could not have got much further from the Wash if they tried"
Now you are just being silly, whether Iceni territority was defined by the Western or Eastern boundary of the Wash it would have been a fundamental piece of their tribal geography. If they considered their tribal lands to include the Wash marshes, well blimey that puts their boundary a mere 25km from Watling St (Huntingdon to Milton Keynes) or 40km St Ives to Northampton. This makes the strategic position of the Wash important for a strike on the Romans (whether dug in or en route) but also brings the Roman force close enough to Iceni territory to comprise an existential threat to the Iceni home lands.

So two points for you to chew on, it will help you firm up your physical geography of the area and be a little less wishy-washy. If you do indeed feel a little less wishy-washy could you crack on with your Akeman St/Fosse Way nomination, your opportunity to make a credible case for a strategy is really undone the more you drift away from making a site nomination :woot: :woot: :woot: I'm happy to help you further with the wetlands but please reciprocate with a nomination and defence. The idea that there are Romans bibbling around on Akeman Street, maybe waiting for reinforcements, maybe busy looking over their shoulders with no vallies to defend seems undefensible, so what is it you are not telling us? After all Bicester (Akeman street) puts you just 20-30km South of Church Stowe.
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Quote:They know the Romans are coming down Watling Street... returning from a recce to London...

If you're really insisting on this 'cavalry dash/recce' then I'm afraid we must agree to differ! Because without such an expedient there is no reason for Paulinus's troops to be so far north.



Quote:I'd sugest they are off for a hunting expedition up Watling Street to finish off the Romans

I've never been too convinced by this idea of the Britons heading off en masse to travel many days and fight a battle with the Romans. From the small amount I've read about comparable popular uprisings against imperial powers from other eras (principally the Indian Mutiny and the Peasant's War in Germany - purely recreational research!) it seems that rebellious tribal/peasant hordes gather strength as they head towards known objectives (places to plunder, symbols of oppression to destroy) and lose it rapidly as soon as professional counter-insurgency forces take the field against them.

The prospect of a disciplined Roman force waiting for them in a position of their choosing is not, I suggest, likely to have the Britons eagerly marching across the countryside to find them, particularly not with their families in tow...



Quote:We "know" they went to Colchester, we "know" some of them went to London and St Albans...a little more discipline please.

Well, being entirely sceptical, we don't 'know' that the rebellion happened at all, or that Boudica existed. We can fairly safely assume she did, and it did, from the accounts in Tacitus and Dio. Beyond what we read in the texts, we must weight our speculations towards the most likely options.

London was probably an important target for the rebels, both strategically and psychologically. A tribal leader like Boudica - although we don't know what sort of command (if any) she really exercised over the rebel army - would probably have wanted to accompany the force that moved against such an objective. Not to do so would have given prestige to whoever led the force in her absence, and her position as leader/figurehead would have been threatened. Speculation, yes, but not lacking rigour, I'd say... Wink
Nathan Ross
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Nathan Ross wrote:

....it seems that rebellious tribal/peasant hordes gather strength as they head towards known objectives (places to plunder, symbols of oppression to destroy) and lose it rapidly as soon as professional counter-insurgency forces take the field against them.

Possibly a hated Governor protected by a small army was enough of an attraction to be destroyed by the tribes especially when he would bring attrition down on their heads because of their actions at Colchester.

John 1 wrote:

.....an East Anglian Peninsula somewhere between Great Chesterford and the Thames, thus delimiting their movement to a particular front....

I would suggest that the southern limit of the Wash was perhaps at the farthest Cambridge and the eastern limit Thetford with the western limit being Godmanchester or Longthorpe.

That is only because these were contemporary sites which wouldn’t be built in the Wash itself I presume.

Having said that Stonea Camp would have been in the middle of the Wash.
This would make the limit of the “peninsula front” about 55 miles which is still pretty broad.
Deryk
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Quote:Possibly a hated Governor protected by a small army

It seems that the procurator, Decianus, was more the focus for native hatred (which makes it even more likely that Boudica and her main army would have gone to London, his headquarters, to find and execute him...) Paulinus, we are told, had spent two years fighting the Welsh tribes, and while he may have made trips to London or Colchester, he quite possibly spent much of his time with the army in Wroxeter etc, and so may have been unknown to the Iceni. Any links they might have had with the druids on Anglesey are conjectural, I think.

The more I think about this, the more I'm inclined to believe (again!) that a Roman withdrawal westwards from London would be the most sensible option. But there's always Paulinus's military cleverness, and the possibility of outflanking - he had to position his army somewhere that the Britons had to fight him. Retreating ahead of them would have posed them no threat. Hanging on their flank, threatening their scouts and supply lines, potentially blocking their route home, might have been a more strategic option... But I'm circling over old ground again here!



Quote:Stonea Camp would have been in the middle of the Wash

Yes, good point. There would surely have been trackway across the fens, so it wasn't an impassible marsh or inlet of the sea. Perhaps the later reprisal campaigns were conducted against rebels hiding out in the fenlands, like Hereward the Wake...?
Nathan Ross
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John,
I am sorry but I am not prepared to re-write history. Our sources tell us that the rebels sacked Colchester, that Suetonius abandoned London to the rebels and that St Albans suffered the same fate. There is no indication that the rebel advance moved in any other direction but away from the Wash. We are also told that, having disposed of isolated garrisons in their own territory, the rebels avoided other Roman posts and sought only plunder. In other words, they did not go hunting for a Roman army to attack. They intercepted Petilius Cerialis who was advancing on them but that was, in effect, self-defence. As to Suetonius' movements after leaving London, we have no information. Nor do we know where the rebels went after the sacking of St Albans. This is where we have to think ourselves into the minds of the protagonists, consider the options open to them and try to settle upon their most likely course of action. We all have our own ideas. I have my personal preference; you have another. I do not agree with it but I am not going to sneer at it.
Michael King Macdona

And do as adversaries do in law, -
Strive mightily, but eat and drink as friends.
(The Taming of the Shrew: Act 1, Scene 2)
Reply
Nathan Ross wrote:

It seems that the procurator, Decianus, was more the focus for native hatred (which makes it even more likely that Boudica and her main army would have gone to London, his headquarters, to find and execute him...)

This argument is one of the best I have encountered for Boudica to go to London but actually it might apply more as a reason for SP going to London.

We can all assume that SP went to London according to the texts.

This was obviously to understand the situation because the procurator had left for the continent and SP had no intelligence and therefore it was paramount for him to go to London to get it and perhaps supplies.

So SP would have no knowledge of the movements of the Trinovantes or the Iceni or the size of the army that attacked Colchester.

He may not have been aware until he reached London that Colchester had been completely destroyed only that the colony had been attacked.

He possibly assumed that the rebels had probably destroyed the Ninth as well.
Consequently as he only had a small army (probably less that 25% and maybe less than 20% of the total military) he wouldn’t risk an advance to the east and so would have to withdraw in order to fight later.

Maybe it was also essential not to let the stores in the warehouses in London (the commercial centre) get into the hands of the rebels and to ensure that he got as much stores as he needed.

Nathan Ross wrote:

Perhaps the later reprisal campaigns were conducted against rebels hiding out in the fenlands, like Hereward the Wake...?

I think that is spot on! :-)
Deryk
Reply
Deryk star performance by bringing Stonea Camp to bear on this, you get a CS campaign medal.

If Stonea Camp and it's road network were known, which we are pretty certain they are, then one could reasonably assume that once the Romans passed it's exit from the Wash around Peterborough, they could not be sure the enemy was not to their rear..... Therefore why would the main body the Roman column proceed further south? So CS again has a good rationale, the route from Peterborough to Watling Street would take the Iceni striaght up the Nene Valley to meet Watling Street at ....Church Stowe. Of course on the way they would have to pass an under garrisoned Longthorpe, a post they by-passed.

It is a distance of 90km, easy navigation, easy water supply even barge-able for some.

[attachment=11955]StoneaNene.jpg[/attachment]


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Deryk gets a CS campaign medal for bringing Stonea Camp into the equation. :grin:

The camp and it's access were known to the Romans, to move South below the camps access to the mainland would ensure the Romans could not be certain the enemy was not to their rear. This makes a pretty good justification for the bulk of the force remaining in the North any move in force to the south would be to invite an attack from both North and South.

An Iceni force exiting Stonea is able to approach via Peterborough (Longthorpe), avoiding contact with it's depleted garrison who could no longer bottle up the Iceni in the Marshes (neat fit with the text). Then the approach to Watling Street is straight up the broad plain of the Nene Valley hitting the Street from the East at a place known locally as Church Stowe. The Nene would have provided sufficient water and ease of transport. Total distance 90km or 55 miles.

Even if the route wasn't used it was a two way threat that would have loomed large in any strategists thinking. An Iceni attack on Watling Street would leave all points exposed if High Cross were taken, and a threat by the Romans to undefended Iceni home territory by the same route through the Wash.

It would make sense for the Romans to commit to a defence south of High Cross but North of, or in, the Nene Valley a window of 36km, 22 miles.

So that's several strategic reasons that CS is still well in the frame.

[attachment=11956]StoneaNene.jpg[/attachment]


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The Akeman Street theory still interests me. It implies many of the same strategic decisions and manoeuvring that would bring a Roman force to Church Stowe. However the late swerve West into a long section with little or no apparently suitable topography still doesn't seem like a winner. It's a long old Road Akeman Street and by the time a Roman got to Alchester he'd be pretty much as far away as Church Stowe, without the added benefit of contact with the new Northern garrisons or High Cross which would therefore be exposed. How far along Akeman are you thinking?

[attachment=11957]AkemanChipolatta.jpg[/attachment]

Glad to hear we'll be dialling back the sneering, this was probably the high sneer point of the thread for me; "What has the Wash got to do with any of this? ..... They could not have got much further from the Wash, if they had tried."


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Quote:The Akeman Street theory still interests me . . . How far along Akeman are you thinking?
In theory, Suetonius could have withdrawn as far as the junction with the Fosse Way, where he could have been joined by troops coming up from the south-west, moving over from the west and pulled out of North Wales. In the event, as I have mentioned before, I see him pausing at the junction with the Icknield Way at Tring. Going back as far as Page 33, Deryk suggested quite a reasonable site for the battle there.


Quote:Glad to hear we'll be dialling back the sneering, this was probably the high sneer point of the thread for me; "What has the Wash got to do with any of this? ..... They could not have got much further from the Wash, if they had tried."
Not sneering, I assure you, just puzzled. I may be being incredibly dense but, with the rebels having moved south to Colchester and then on to London, I fail to see the relevance of the Wash.
Michael King Macdona

And do as adversaries do in law, -
Strive mightily, but eat and drink as friends.
(The Taming of the Shrew: Act 1, Scene 2)
Reply


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