"I said leave some of your forces to defend the villages. The rest should march out, as a single unit, to form a line and separate the two enemy forces. Cut off their communications between the two of them."
"To stop them coordinating an attack from opposite directions," Gaius nodded. "They can still get inspired and try to encircle me, though, but. ."
"But?"
"I don't want to look like I'm fighting yesterday's battle, but I guess if that happens I just have to fight my way out through the weakest point."
"Encircling is all very well when things are going your way, or if the enemy is set on defence, but against an enemy intending to attack, all you do is thin your line. ."
"Because his line has to be longer to get around you," Gaius nodded. Timothy would be talking about geometry in any minute.
"However," the older General smiled, "suppose they don't encircle you? Now what?"
"I suppose I attack one of the enemy forces," Gaius offered, then quickly added, "That was the thought, not the order of battle!"
The older General smiled. "Then what do you do? Assume you have four cohorts, including the first?"
"If the two forces are equal, I go for the one where I have the most favourable terrain," Gaius said, "while if they're unequal, I go for the weakest. I put the first to guard the rear, in case the other force gets inspired, and in the absence of any further information about terrain or their deployment, I attack the centre with two cohorts, and I try to turn the right flank with the last cohort."
"That's fairly standard stuff," the General frowned.
"I can't see any reason to be different. ." Gaius began to protest.
"Good!" the General interrupted. "Your problem is that sometimes you are just too imaginative. Tried and tested is just what you need, most of the time. You're right to go for the weakest opponent first, but do it quickly, before the other works out what you're up to. Defeat that, then march towards the other. If the enemy splits, divide him with a single force, then concentrate your attack on what you think will be his weakest force."
"Suppose," Gaius said, "they decide to attack? They've already encircled me."
"The other way of looking at it is that you've already punched a hole through their lines, and they have two forces who can't communicate with each other, and who can't coordinate such an attack. In any case, when you first looked at this problem, you split your forces and went out to meet them, without adequate communication, so presumably you think you can defeat them, and half of your forces can at least hold out against all of theirs."
"What do you mean, half of my forces can hold out?"
"They can always regroup into one unit while you're marching," the older General said, "and not only that, they could have sent disinformation to get you to split, intending to knock you out half at a time."
"But. ." Gaius was about to protest.
"No buts," the older General wagged his finger at him. "Not everything you hear will be true. As for your complaint, if they attack on both sides, form a square and let them pound away. They will find it most expensive to attack a properly set defensive square. And anyway, you are crediting the opponent with his best option. Most of the time they don't take them, and again, if they do, they were always going to be good enough to give you a problem, which is all the more reason for you to take your optimum strategy. If your opponent is brilliant, marching out between them gives you your best chance if you must march, while if he is substandard it gives you the chance to wipe the field with him, at minimum cost."
"I see," Gaius nodded.
"Do you?" the General smiled. "You wish to alter your second marching orders?"
"I can't see why. ." Gaius started, then paused. He must be wrong, but where. "Perhaps. ."
"Never give an order starting with perhaps!"
"I was thinking to myself," Gaius replied tartly, then suddenly felt silly. "I'm sorry," he said. "I march my legion to the south of the river, and to the south of the enemy so that I can meet them where they have no room to retreat, and they cannot manoeuvre in depth."
"Better," the General nodded. "You're getting the idea. Think in terms of warring on a square. The east is his zone, where he came from. In this case the north is fairly inaccessible, and as you rightly noted, the river acts as a barrier. Your base is from the west, so who controls the south?"
"I do, because I've marched out in that direction."
"No, you are trying to. You've probably got the idea to some extent, but spell it out. Your marching objective is to march towards the south west of him, or even the south, or even better still, the south south east if you can do that without his knowing. Then the enemy has no easy line of retreat, and if you can get into position before he finds out what you are doing, you have half won before you even start fighting."
"How can that matter? There're no natural advantages."
"Think about it from the point of view of a foot soldier who really wishes he was back with his family. He's marching forward, thinking of loot, then a major force appears from his left rear. Why? What he thinks is you are trying to cut him off from his family, so he goes into the fight with half his mind thinking of ways to get out of there.
"If you can deploy before the enemy commander can set his forces properly, you have a further advantage. By simply sitting there you give him a problem. He has to give up on his primary objective, and decide whether to enter battle with no hope of retreat, or try to find a way past you. He can't attack the village, even though there are hardly any forces between him and it, because he opens his rear to an undefended attack. If your primary objective was to protect the village, you have achieved that before any fighting commences."
"I suppose," Gaius said, in a flat tone, "although he could stand and fight with most of his forces, and attack the village with a small part of his force. I can't stop him."
"If he splits some of his force, as you say, they are either infantry of cavalry. What do you do if they're infantry?"
"Chase them with cavalry," Gaius nodded.
"If they're only a small squad, they'll be cut to pieces," the General said. "If they're a major infantry force, either you clean out that which stands against you, or you were always so outnumbered you were never going to succeed. What do you do if they send cavalry?"
"I. . suppose I have to send cavalry as well," Gaius frowned.
"No, you don't," the General said. "Let the defensive walls about the village buy you time. Unsupported cavalry can't do much about them. Send your cavalry into the rear of his infantry, and support the attack with infantry. If you attack quickly, his best troops are going to be the last to join battle, because they're up the front. There may well be a full flight before they get to engage. If he launches some sort of attack against you at this point, better still, because he will have committed himself before he is ready. Use some infantry to defend the first attack, while striking hard elsewhere, and against most barbarians, they'll offer their backs. And even if they fight like fiends, so what? They always would have. You may argue this set-up is artificial, and you'd be correct. It is, but that's not the point. What I am trying to get you to recognize is that you can achieve considerable advantage merely by directing where you march. Looking at it the other way, suppose you were the enemy, which way would you march, and why?"
"Me, I would direct my force in a line half-way between the villages, then when I was in between, attack whichever one I thought was easiest."
"See," the General smiled. "You do that because if they have to defend two villages, they have to split their forces, so you pick them off singly. You achieve that because your line of approach is not directed at either. The straight line between two points may well be the shortest line, but it is not often the best line of attack. The more ambiguity in the enemy's mind, the better. Think about this, and we'll try again tomorrow."