They explained everything by turns, starting with the most important facts. The location was crucial, either up on a mountain like Beaufort or out in the water like Arnäs. But no matter how good the position for defensive war, they needed to have water inside the walls, not a spring outside that the enemy could find and cut off.
Equally important as access to water and a good position was the ability to store sufficiently large supplies of food, most importantly grain for bread and fodder for the horses. Only then could they begin to think about the construction of the walls and moats that would prevent the enemy from raising siege towers or bringing up trebuchets to fling stones and offal into the castle. And the next most important thing was the placement of the towers and firing positions so that they could cover all the angles along the walls with as few archers as possible.
Arn drew towers that protruded beyond the walls on every corner, explaining how from such towers they could shoot along the walls and not merely outward. In this way they could minimize the number of archers needed up on the ramparts, which would be a great advantage. Better shooting angles and fewer archers were essential.
Here Eskil interrupted, a bit reluctant to show his ignorance at not understanding the advantage of having fewer archers, which seemed to be a given for Arn and the monk. What did they gain by reducing their forces atop the walls?
Endurance, Arn explained. A siege was not like a three-day banquet. The point was to endure, not to let weariness reduce their vigilance. Those who laid siege to a castle wanted to take it by storm in the end, if not by negotiation. The besiegers could choose any time at all: after a day, a week, or a month; in the morning, at night, or in the broad daylight of the afternoon. Suddenly they would all appear at the walls with siege ladders, coming from every direction simultaneously, and if they had been diligent in hiding their intentions the defenders would be taken completely by surprise.
That was the decisive moment. Then it would be crucial that the defenders positioned up on the walls would have been on duty only a few hours. And that two-thirds of the defending force were rested or sleeping. When the alarm bell rang it should not take many seconds before all those who had rested were at their battle stations. If they practiced this several times, the defensive force of the castle would increase from one-third to full force in the same time it took the attackers to bring forward their siege ladders. So sleep was an important part of their defence. With this arrangement they also saved many sleeping berths, since a third of the defenders were always on the walls. And they also had a spot warmed up when they came down from duty.
But back to the fortress of Beaufort. It was indeed one of the strongest in the world, but it was located in a country where it was important to defend against the mightiest armies in the world. It would take ten years to build such a castle at Arnäs, and it would entail much extra work for no good purpose. Or, as Arn explained with a glance at Eskil, it would involve spending too much silver. A war such as that in the Holy Land, with such armies, would never come to Arnäs.
Arn erased the picture of Beaufort with his foot and began to draw Arnäs as it would one day become, with a wall enclosing more than twice the present area. The entire tip of the point would be fortified, and where the point turned into marshland a new gate would be built, but higher up on the wall. Then they would also have to build an equally high ramp of stone and earth with a moat between the wall and the bridgehead on the other side. In this way no one would be able to bring up battering rams against the gate, which would be much weaker than the stone walls no matter how strongly it was constructed. A gate at ground level, like they had now, was an invitation for the enemy to hold a victory feast.
If all this was done according to plan, Arn assured them that with less than two hundred men inside he would be able to defend Arnäs against any existing Nordic army.
Eskil then asked about the danger of fire, and both the monk and Arn nodded and said it was a good question. Arn started drawing again, describing how the courtyards inside the walls would be paved in stone, and all the sod roofs would be replaced with clay slate. Everything flammable would be replaced with stone, or in the event of siege they would be protected by ox-hides that would constantly be kept wet.
And these were just the ‘defensive’ measures that needed to be taken, Arn continued eagerly now that he saw he had captured Eskil’s interest. The other part was to mount an attack themselves. It was best to do that with troops on horseback, and long before the enemy began a siege. It would be an immense and slow undertaking to move an army to lay siege to Arnäs. On the way there the enemy’s supply column could be attacked by mounted troops on horses much faster than their own, and this alone would take a toll on the enemy’s strength and will to fight.
And after the siege had gone on for a week or so, and the enemy’s alertness had diminished, the gates of the castle could be suddenly flung open and out would stream horsemen with full weaponry, able to take many times more lives than they lost. Arn drew strong lines on the ground with his dagger.
Eskil couldn’t help feeling confused at how differently war was waged in lands outside the North. He thought that he understood Arn’s reasoning; that what was already happening out in the world would sooner or later make its way to Western Götaland. So it would be best if they learned the new techniques and built up their strength before their enemies did. But how would all this be accomplished, in addition to the construction work?
Skills were an essential part of the endeavour, said Arn. And he and many of his foreign guests had mastered those skills.
Silver was the other part. The way war was waged in the world at large, the one with the most silver became the strongest. A mounted army did not live on air or on faith, although both were necessary; the soldiers needed supplies and weapons, all of which had to be bought. War in this new age had more to do with business, rather than the willingness of kinsmen to protect each other’s lives and property. Behind every fully armed man in chain mail stood a hundred men who cultivated the grain, drove the ox-carts, burned charcoal for the smithies, forged weapons and armour, transported them across the seas, built the ships and sailed them, shoed the horses and fed them – and behind it all were vast sums of silver.
War was no longer two peasant clans fighting about honour or who would be called king or jarl. It was business – the biggest business in the world.
Whoever managed this business with good sense, plenty of silver, and sufficient skill could buy the victory if war came. Or even better, buy the peace. For he who built a strong enough fortress would never be attacked.
Eskil was struck by this sudden insight that he and his business dealings might be more important for war or peace than all his guards put together; he was speechless. Arn and the monk seemed to misunderstand his waning questions, thinking that he was tiring of the lesson, so they immediately prepared to remount their horses.
They visited three quarries that day before Arn and the monk seemed to find what they were looking for in the fourth one, which had only recently begun cutting sandstone. There were few stonecutters, but there was a supply of cut stone blocks that had not yet been sold.
This would save a great deal of time, Arn explained. Sandstone was often too soft, especially if used in walls that were subjected to heavy battering rams. But they didn’t have to prepare for that sort of battle at Arnäs, because the ground out on the point rose steeply up to the walls, with no possibility of deploying battering rams. And to the east toward the moat and drawbridge, the ground was far too soft and dropped off too abruptly. So sandstone would serve the purpose well.
Sandstone also had the advantage of being easier to cut and shape than limestone, not to mention granite, and here they already had a supply that could be used in construction without further delay. This was good. Choosing the right type of stone would save more than a year in construction.
Eskil made no objections. Arn thought that his brother seemed unexpectedly amenable when he agreed to every decision regarding the work that would have to be done at the quarry the following week, and where and how new stonecutters would be acquired.
But he did complain about having a serious thirst. He gave Brother Guilbert