Calling all armchair generals! Boudica's Last Stand.

[Renatus]

I'm not sure that Cerialis wouldn't have brought half his legion with him, even if he had to leave the other half to guard the northern approaches. If he was marching into enemy territory he surely would have taken all his available troops?

But you're right that Tacitus doesn't explicitly say that the 9th lost 2000 men: "...two thousand legionaries, eight cohorts of auxiliaries, and a thousand cavalry. On their arrival the men of the ninth had their number made up with legionary soldiers." So some of the 2000 could have gone to make up losses in other legions, as you suggest.

I do wonder whether Cerialis would have marched without any orders from his senior, Paulinus, though - if he did, he would probably have received greater blame for what subsequently happened. His reckless advance on Colchester reads a bit more like the act of an ambitious subordinate interpreting his orders liberally, rather than an entirely independent action. Then again, we know so little about how orders and requests were passed up and down the chain of command.

I have long held the view that, on hearing of the revolt, Cerialis would have hot-footed it to Longthorpe ready to lead the garrison there against the enemy.  I did not think that would be alone in that but am glad that someone else has put it into words.  I am doubtful, though, that he would have left any able-bodied men there, when he marched out to the relief of Colchester.  He would need everyone available.  What he could have done is order a body of men, possibly veterans, to follow him from Lincoln to guard Longthorpe until the garrison returned.

The issue then is when he marched out.  If we are right in thinking that Suetonius' plan was to rendezvous with Cerialis and to lead their combined force against the enemy, he would have sent a message to him to gather his troops and wait until he could join him.  Cerialis could not have avoided censure for disregarding such an order, unless there was a good reason to do so.  As I have said before, it is likely that he realised that the situation was critical and that Suetonius could not get to him in time and, even then, he was too late to save the colony.  Despite Tacitus' criticism of him for being reckless, the setback does not seem to have damaged his career and it is likely that those who mattered accepted that he had little option.

As to the allocation of the 2000 legionaries sent from Germany, I would expect that all or most of them would have gone to bring the Ninth up to strength.  The figure is very likely rounded up or down and the actual number could have varied by a few hundred either way.  However, I feel that it is more likely to have been rounded down.  In any campaign, such as Suetonius' assault on Anglesey, there are bound to be casualties but I am inclined to think that these would probably have been made good by normal recruitment.  However, when a unit suffered a massive loss, as the Ninth evidently did, my guess is that the inclination would be to direct reinforcements to bring that unit as near as possible to full strength.