It sounds fantastic. At any other period it would have been impossible. Yet in the Year of the Four Emperors, when the whole Empire blazed in ruins while the imperial contenders slogged it out, this was just one especially colourful sideshow amongst the wide-scale lunacy.

I wondered glumly how the colourful Rhenus frontier was about to impinge on my drab life.

'We have Germany in hand,' Vespasian declared. From most politicians this would have been self-deception. Not him. He was a good general himself, and he attracted strong subordinates. 'Annius Gallus and Petilius Cerialis have achieved a dramatic turnaround.' Gallus and Cerialis had been sent to subdue Germany with nine legions. It was probably the largest task force ever sent out by Rome so success was a foregone conclusion, but as a loyal citizen I knew when to look impressed. 'I'm giving Cerialis the governorship of Britain as a reward.' Some reward! Cerialis had served in Britain during the Boudiccan Revolt, so he would know what dismal privilege he had just won.

A lucky fluke reminded me that the esteemed Petilius Cerialis was related to Vespasian. I swallowed a witty rejoinder and asked meekly, 'Caesar, if you can spare Cerialis for higher duties, the frontier must be under control?'

'Some unfinished items-I'll come to those.' Whatever was said in public, the whole region must still be highly sensitive. Not the time for a quiet cruise downstream on a wineship. 'Petilius Cerialis held a meeting with Civilis-'

'I heard about that!' Dramatic stuff: the two opposing commanders had confronted each other in the middle of a river, both bawling across the void from the ends of a severed bridge. It sounded like some incident from the mists of Rome's heroic history that schoolboys learn about.

'Civilis has fallen unnaturally quiet since then:' Speaking of the rebel chief, Vespasian paused, in a way that ought to have worried me. 'We were hoping he would settle down peacefully in the Batavian homeland, but he's missing.' That did arouse my interest; I read in it a bad prophecy for me. 'Rumour says he may have travelled south. On that subject, I'd like to say to you-'

Whatever he had intended to tell me-or warn me-about the rebel Civilis never happened, because just then a curtain swung open and the official who must be the one he had called Canidius arrived.

When he shambled in, the sharp lads in glittering white uniforms who waited on the Emperor all stepped back and glared at him bitterly.

He was a real papyrus beetle. Even before he opened his mouth, I guessed he must be one of those odd cases who hang around secretariats doing jobs no one else will. No well-kept palace would tolerate him unless his contribution was unique. He wore a dingy damson tunic, shoes with one lace tied up crookedly, and a belt so poorly tanned it looked as if the cow it came from was still alive. His hair was lank, and his skin had a grey pallor that might have washed off when he was younger, but was now ingrained. Even if he did not actually smell, he looked musty.

'Didius Falco, this is Canidius,' Vespasian himself introduced us in his brisk way. 'Canidius keeps the legionary archive.'

I was right then. Canidius was a clerk with unpromising prospects who had found an offbeat job he could invent for himself. I grunted noncommittally.

Vespasian shot me a suspicious glance. 'Your next assignment, Falco, is as my personal emissary to the Fourteenth Gemina in Germany.' This time I saved myself the hypocrisy of politeness and openly grimaced. The Emperor ignored it. 'I hear the Fourteenth are in a truculent mood. Brief us, Canidius.'

The eccentric-looking clerk recited nervously, without notes. 'The legio Fourteenth Gemina were an Augustan creation, originally raised at Moguntiacum on the River Rhenus.' He had a thin whine of a voice that tired a listener rapidly. 'They were among the four legions chosen by the Divine Claudius for the invasion of Britain, acquitting themselves bravely at the Battle of the Medway, much assisted by their native auxiliaries, who were Batavians.' North Europeans from the Rhenus delta, Batavians are rowers, swimmers and river pilots to a man. All Roman legions are supported by such units of foreigners, in particular native cavalry.

'Falco doesn't need your Claudian anecdotes,' muttered Vespasian. 'And I was there!'

The clerk blushed; forgetting the Emperor's history was a bad mistake. Vespasian had commanded the Second Augusta at the Battle of the Medway, and he and the Second had played a celebrated part in the conquest of Britain.

'Caesar!' Canidius writhed in misery. 'The Fourteenth's roll of honour includes defeating Queen Boudicca, for which-along with the Twentieth Valeria-they were awarded the honorific title of "Martia Victrix".'

You may wonder why the Second Augusta did not win that prestigious handle too. The answer is that due to the kind of mix-up which we like to pretend never happens, the wonderful Second (my own legion as well as Vespasian's) failed to show up at the battlefield. The legions which did face the Iceni were lucky to survive. That was why any member of the Second needed to avoid the Fourteenth Gemina, honorific titles and all.

Canidius went on: 'In the recent wars, the Fourteenth's Batavian auxiliaries featured crucially. They had been separated from their parent legion and summoned to Germany under Vitellius. The Fourteenth themselves were devoted first to Nero-since after the Boudiccan Revolt he had called them his best legion-and then supported Otho. Otho brought them to Italy. This placed the legion and its native cohorts on opposing sides, and at the first battle of Bedriacum:' Canidius tailed off unhappily.

He was intending to fudge the issue, so I barged in: 'Whether the Fourteenth Gemina actually took part at Bedriacum is a moot point. Rather than admit they had been beaten in battle, they claimed they had not been there!'

Vespasian grumbled under his breath. He must think they were simply covering up.

Canidius rushed on again. 'After Otho's suicide, the legion and its auxiliaries were reunited by Vitellius. There was some rivalry,' the archive clerk said, with quaint discretion. He had no real grasp of what the Emperor required.

'You're leaving out the picturesque details!' I interrupted. 'Be frank! The Fourteenth's subsequent history involved squabbling and public scuffles with their Batavians, during which they burned down Augusta Taurinorum:' This episode at Turin placed the main question mark over their discipline.

Wary of handling a sensitive issue, Canidius raced to finish. 'Vitellius ordered the Fourteenth itself back to Britain, attaching the eight Batavian cohorts to his personal train until he redeployed them in Germany.' More politics. Canidius was looking unhappy again.

'In Germany, the Batavian cohorts promptly attached themselves to Civilis. It gave the rebellion a tremendous boost.' I was still angry about it. 'Since Civilis is their chief, the Batavians' defection should have been foreseen!'

'Enough, Falco,' rasped Vespasian, refusing to criticise another Emperor-even the one he had deposed.

He nodded encouragement to Canidius, who squeezed out: 'The Fourteenth returned from Britain again to assist Petilius Cerialis. They now occupy Moguntiacum.' He finished his tale with relief.

'Only the Upper German forts survived,' Vespasian told me crisply, 'so Moguntiacum is at present policing both parts of the territory.' Clearly while the fort where they were stationed had such a vital role, he needed to feel absolute confidence in the Fourteenth. 'My priority is to tighten up discipline and dissipate old sympathies.'

'What happens to the troops who swore allegiance to the Gallic federation?' I asked curiously. 'Which were they, Canidius?'