A couple of cups of wine later Pallas returned brandishing a wax tablet. ‘It’s done, domina,’ he announced. ‘It’s a substitution cipher such as Caesar used, but with a rolling shift, based on the number twelve. So the first letter you shift by one, so A becomes B; then the second by two, so A becomes C; the third by three and so on up to twelve. Then you start again but this time you shift the next letter by two, the next by four, then six, eight, ten, twelve. Then you continue with the next letter shifted by three, then six, nine, twelve. Then you do fours, then sixes and then twelve itself, after which you start again with one and so on. Very simple really.’
‘Very good, Pallas.’ Antonia looked as baffled as everyone else around the table. ‘So what does it say?’
Pallas cleared his throat and began to read aloud.
‘“I send my greetings” etc., etc.; then:
‘As you are aware, my master has an agreement with your mutual friend that he will support my master as and when the time comes. However, my master now feels that once he has achieved his aim that friend will move to eliminate him and take his place through a familial right. In order to counter this, my master proposes to free himself immediately he has gained his rightful position and thereby cut the tie to the friend and therefore any legitimate rights he may have. In place of what he loses my master would take what is dearest to you, bonding himself with you, in order to still be able to expect your support, with its full force, at the appropriate time. He realises that certain arrangements would need to be made in advance and suggests that you make them sooner rather than later. He would have you know that he has made similar, though not, of course, the same arrangements with other people of your calibre and would hope that you would see the sense in joining his cause, rather than opposing it, as he would value your and your family’s support highly in the endeavour that he feels is nearing fruition. He awaits your reply.’
There was a stunned silence in the room; all the men turned towards Antonia. The expected explosion did not come; instead she just nodded her head slowly as she digested the barely veiled meaning of the letter.
‘It seems that you may be right after all, Gaius,’ she said eventually. ‘Claudius the booby isn’t quite as stupid as I thought; he’s hidden it well.’
‘That’s why he’s still here, domina,’ Gaius replied quietly, knowing all too well the fragility of Antonia’s temper when it came to discussing her two surviving children. ‘We need to work out what this means for us. I assume the mutual friend is Sejanus; so it seems that he has already got his support to succeed Tiberius.’
‘What a fool I’ve been,’ Antonia whispered, gazing into the middle distance. ‘When Tiberius suggested that Claudius marry Aelia Paetina I jumped at it, thinking that he was using Claudius to give something to Sejanus that he had always wanted: a connection to the imperial house, without giving him anything of value because his sister was marrying someone who could not possibly aspire to anything. How wrong I was. Sejanus is going to make Claudius Emperor, then depose him and take over as his legitimate brother-in-law; he’ll then secure his position by marrying my daughter Livilla. Claudius recognises this threat and is preparing very sensible precautions: divorcing Aelia Paetina once her brother, Sejanus, has made him Emperor and she is of no more use, thereby taking away Sejanus’ claim to legitimacy. Then he’s going to marry Poppaeus’ daughter Poppaea Sabina, thus ensuring her father’s support for her new husband with his full force of the Moesian legions and all his auxiliary cohorts. She’ll have to divorce her husband, Titus Ollius, with whom she’s just had a daughter, another Poppaea Sabina; that must be the arrangement Claudius wants Poppaeus to make. Well, that’s no great hardship, he’s nobody, and Poppaeus won’t be able to resist the chance of his daughter becoming Empress. The other people of influence he’s approached must be the Governors of provinces with legions close to Rome: Pannonia, Africa and on the Rhine. He’ll try to make himself unassailable and one of his first victims will be my little Gaius. I will not let this happen.’
‘It won’t happen, domina,’ Vespasian said with some confidence, ‘because you’re ensuring that Sejanus will fall. Without Sejanus surely Claudius is impotent?’
‘Not necessarily; if he has ambitions to be Emperor, however ludicrous that may seem, then he won’t let a setback like losing an untrustworthy ally stop him. He’ll resort to another strategy, the only possible alternative in the absence of anyone willing to aid him: murder. If he really is as ruthless and cunning as that letter indicates then his obvious course of action would be to clear the way to the Purple by removing all potential rivals; and again my Gaius will be one of his victims. Claudius has to be stopped but, short of killing my own son, I can’t as yet see how.’
Pallas cleared his throat quietly in the corner.
Antonia smiled. ‘You no doubt have a suggestion, Pallas.’
‘Never, domina; but perhaps I may be permitted to make some observations?’
‘I never tire of your observations.’
‘You are most gracious, domina,’ the steward said smoothly, stepping forward into the room. ‘There’re a few things that occur to me. Firstly: the letter states that Poppaeus is aware of the arrangement between Claudius and Sejanus; therefore, at least the three of them, but probably more, must have met to discuss the deal whilst Poppaeus was recently in Rome.’
‘So who else was there?’ Gaius asked.
‘The people of “calibre”, as my mistress suggested, the other Governors or their representatives. At that meeting they would have pledged the support of their legions; you’ll notice that it says: “ still be able to expect your support”.’
‘So what has he offered them to keep them on his side?’ Vespasian mused.
‘That brings me on to my second point: Claudius must assume that Poppaeus has just as much interest in his becoming Emperor as he has in Sejanus deposing him — he is close to both of them and would gain by whoever wore the Purple — otherwise he wouldn’t have made as big an offer as to make Poppaea Empress. He must believe that this will tip the balance in his favour otherwise he would not be making him party to his thwarting of Sejanus’ ambitions.’
Vespasian smiled as he saw the major flaw in the plan. ‘But he can’t offer as high an incentive to the others, so one or two of them are bound to be disappointed and may decide to throw in their lot with Sejanus, in which case Claudius’ scheme is bound to be revealed.’
‘Exactly; so Claudius seeks to counter that by a threat, which he must have made in various forms in the other letters he wrote; he gives Poppaeus a clear choice: with him or against him, no middle ground. He then, in the same sentence, goes on to mention his family; in other words: Poppaea is either Empress or dead.’
‘And if, by some chance, he was to become Emperor,’ Sabinus said slowly, ‘and he went through with that threat against Poppaeus or any of the other Governors who stood against him, they would be obliged to take revenge, for the sake of their dignitas, and-’
Antonia cut in and finished his sentence: ‘We would be plunged back into civil wars as destructive as those in my father’s time.’
‘But I don’t believe it would get that far,’ Pallas continued, ‘because, as Vespasian has pointed out, Sejanus is bound to hear of Claudius’ plan from one of the Governors who’s not been offered enough; in fact he probably already knows about it, as this letter was found four months ago and it’s reasonable to assume from the wording that the other letters were sent at the same time.’