"We were forced to accept, right from the outset of our campaign in Britain, that we could never hope to react in time to have any preventive effect upon this type of enemy incursion. We had to evolve new tactics to deal with new conditions, and so we split our forces, our cavalry forces, regionally, into five central bases: one in Eboracum, one in Glevum, one in Verulamium, one in Dubris and one in Noviomagus. Using each of these bases as the hub of a wheel, we set up lines of observation — outposts of infantry — tending signal-fires along lines radiating from the centre. Once these lines were established and in place, the news of raiders passed as quickly as the visibility of the fires. Sometimes the ancient methods are still the best — we simply adapted the signal-fires to our own needs, and used more of them. And while we were setting up these beacons, we also set up relay stations along the same lines, fully staffed and equipped with fresh horses. We split our active troops into self-sufficient squadrons with one centurion in overall charge of each, two decurions and forty troopers. Our reasoning in this was that one longboat could contain anywhere from thirty to fifty men. Two boatloads would double that potential, and so on. Our arithmetic considered one squadron of disciplined cavalry to be at least the equal of two boatloads of raiders, so each relay station was stocked with eighty-eight horses, kept in a constant state of readiness.
"Each outpost was responsible for the building and the maintenance of groups of five signal-fires, set up side by side in a straight line and far enough apart to avoid any confusion. One fire meant one boat. Four fires set alight simultaneously meant more than three boatloads — a heavy raid. Five simultaneous fires means more than six boats — a major invasion fleet. It works very well, for our whole operation is predicated upon the advantage held by a double squadron of heavily armed, well-mounted, disciplined troops over a body of men on foot numbering twice their strength or even more. When four signal-fires are lit at once, for example, three squadrons are dispatched in response. Two of these ride at speed to catch the enemy on land, at work, and keep him from retreating to his boats. The third proceeds more slowly, in reserve, backed up by a full cohort of infantry moving at a forced march."
"It sounds good," said his father. "How well does it work?"
"As well as we can hope for. Our major weakness, at the start, was that we did not have enough good horses. It takes a lot of horseflesh to implement a plan like that. In the beginning we were operating at half strength in every area. We had to. We could not simply neglect some areas in favour of others, since we had no idea where the next spate of landings might occur. But the signal-fires passed the word quickly and our response time was very fast. As the Tightness of our method began to prove itself, Stilicho moved heaven and earth to appropriate more and better horses for us. He used to joke that he was stripping the Empire clean of horseflesh to feed the people of Britain, and there were times when it looked as though it might be true. It seemed that every second Roman galley arriving in Britain was loaded with prime horseflesh."
"Impressive," I said. "How soon after your arrival did you start to put all this in place?"
"A matter of months. As soon as we grew tired of looking foolish every time we arrived on the scene of a raid to find all the damage done and the enemy gone."
"Which was often?"
"Always would be more accurate."
"I see. And since you switched over to these new tactics all of that has changed? Whose idea was it to set up these regional bases?"
He shook his head. "No one's, and everybody's. The idea came out of a staff meeting. I mentioned the possibility of splitting our forces to gain manoeuvrability, and the idea grew from there. By the time that meeting had ended, the rudiments of the plan were in place and the logistics were under consideration. From that point onwards, it was just a matter of time until we had our units positioned and ready to move at the sight of a beacon. Once the troops were distributed, it became a matter of tightening up our procedures, learning from our mistakes and adapting to conditions as they arose."
He stood up, stretching himself. "I can give you an example of what I mean by that, too. One of the first things we learned was that, almost invariably, when there was only one boat involved in a raid, the enemy was gone by the time we arrived, no matter how fast our response was. They hit, cleaned up and got away in a hurry. As soon as a raid involved two or more boats, however, their operations time slowed down very considerably. We really don't know why this should be, but we suspect it was because of their numerical strength. It seemed to give them the confidence to move further inland. Of course, with twice the men, they needed twice as much booty to be equally successful. Anyway, a pattern began to emerge very quickly and it indicated that it simply was not worthwhile dispatching troops against a single-boat raiding party.
"There are people, I know, who think that was a callous decision. But it was the only one we could make, the only one that made any sense. At the height of the raiding activity in the early summer of the first year we were in action, there were four occasions when we were short of men to tackle major raiding parties because troops had already been dispatched to minor raids, and on none of these four occasions did our squadrons make contact with the small raiding parties. They were gone, back out to sea before our people ever came near them. Standing orders were changed to alert troops to one-boat raids but to respond only to raids involving two or more boats."
"Makes sense," I said. "If what you say is true, and I don't doubt a word of it, the people in the farms and villages along the coastline who were being hit by these small raids were beyond help in any case."
"Exactly. But a strange thing has happened in the course of two years. Do you know that there is now an almost uninhabited belt, ten or twelve, sometimes fifteen miles wide, around the entire coastline of southern Britain?"
I shook my head. "No. You mean the people have just moved out?"
"Most of them. Moved inland. A few stayed, too stubborn to move away from their homes and their living — mainly fisher-folk who live right on the coast — but the majority, the farmers and farm workers, just abandoned everything and moved inland to safety."
"How has this affected the raiders and their methods?"
Britannicus was watching his son closely, a tiny frown ticking between his brows.
Picus shook his head decisively. "It's too early to say with any kind of certainty, but we are pretty well convinced that it has had an effect — and a positive one — on the number and the nature of the raids. Single-boat raids are almost non-existent now. It takes a lot of guts for one boatload of thirty-odd men to travel inland for ten or fifteen miles in the hope of finding a village, hitting it and getting out again before our people arrive. It puts a lot of distance between them and their boat."
"But your people don't respond to one-boat raids, you said."
"They would now, knowing that the enemy is going to be on foot for fifteen miles inland and back. But it simply doesn't happen any more."
"So raiding parties are getting bigger?"
"Yes. That's absolutely correct. And fewer, too."
"So how much thought have you given to future developments in this pattern?"
Picus flashed a grin at his stern-faced parent. "We hope it develops to the point where all of them land together and we can smash them once and for all, but that's a dream. If the trend continues, and at this time it is only a suspected trend which time will prove or disprove, but if, as I say, it continues to develop, then we could see numerically stronger parties raiding more systematically next year."
"And how will that affect the deployment of your cavalry?"