The Eve of the Decisive Battle (Day 3, Evening)

[East Side of the Valley Before the Dungeon] The Tsukuba Camp

"This is the worst."

Tsukuba Naiyaku-no-jō muttered it so his subordinates wouldn't hear.

"My lord, is something the matter?"

"No, I was only thinking about how to take that city wall."

A sheer wall, fully a hundred shaku high or so, stretched on and on.

"My lord, an ordinary rammed-earth wall, packed and beaten into shape, could normally be broken down with a battering ram, but that thing is a dungeon any way you look at it."

"It's quite a bit taller than I expected."

"They mean for us to throw everything at the gate. No turret, not even a proper door, so it plainly looks like the weak point, but that is exactly the trap."

"Just so. Do not go near the gate. If it were an ordinary castle this might be nothing but an empty-fort ruse, but since it is a dungeon, there is certainly a trap."

"Even so, we have no ladder a hundred shaku long."

"Bufo, bufo. What do you suppose I dragged the whole baggage train along for? The whole army crosses the valley and encamps south of the gate, at a distance the wall's arrows can't reach. Whatever you do, do not go to the front of the gate."

"The whole army, my lord?"

"Common sense would say to set up a separate main camp on the near side of the valley. But the enemy is few. Better to bivouac in one place. Line up our empty handcarts on the enemy's side and make a wall of them."

"My lord, how can you tell the enemy are few?"

"Twenty, thirty at most. They've just scraped together a mob of peasants to pad out their numbers. Being of the water element, I'd have thought they might keep a turtle or some such as a dungeon monster, but turtles are useless, so I suppose they never summoned one."

The turtle is a creature of the water phase.

"My lord, the gate being a trap, then how do we get over the wall?"

"A trap, once you know its true nature, can be dealt with. I'll explain the details tomorrow morning. There's no telling where a spy might be lurking. It would be a problem if they took countermeasures during the night."

"The true nature of the trap, my lord."

"There will surely be a pit trap and a buried fire. There are candidates for other traps as well, but those are better left unsaid."

Naiyaku-no-jō's plan was this: make them think he meant to attack the gate, then pile the empty handcarts with earth and rubble, ward off the arrows with the cart-walls as he heaped the earth higher and higher, and storm over with ladders at the last. A tactic possible precisely because the enemy force was so very small.

[Core Room]

"The enemy unit isn't stopping at 'Minami-Nakano' on the far bank of the valley. It looks like they're setting their main camp at 'Amanuma,' on the near side, the wall side."

Mint reported. The bivouac was not directly in front of the gate but pitched to the south of it, off the highway. The enemy troops were walking about, prodding the ground with poles as they went.

"What are they doing?"

"Watching out for pit traps, I'd say. A while back, before Rāja arrived, we dropped some pirates into a pit and roasted them alive. We had no horse at the time, so one of them got away, which means they probably know the danger of pit traps too."

"A method only a dungeon could pull off."

"Of course, even now the gate's barbican mouth is one giant pit trap. A commander sharp enough to see through an empty-fort ruse would attack at once, but this one seems to have a bit more sense than that. I did think of laying a minefield while we were at it, but clearing it afterward is a nuisance, so I gave up on the idea. I'll cheerfully step on a verbal mine, but I have no taste for stepping on a physical one."

An Asura, of all beings, is unfazed by carnage.

"There's no horse-bay outpost or square barbican, then."

In front of the gate, Kawagoe Castle has a half-moon horse-bay outpost and Iwatsuki Castle a square one. The square barbican set inside the gate is the kind Edo Castle has.

"Bending the road would only get in the way of traffic, and once the dungeon's sphere of influence widens, the enemy will rarely make it this far at all."

"Rarely?"

"Asura though I am, I can't be so conceited as to declare it zero."

Before long the enemy's bivouac was complete. The trailing baggage train was taken in behind it.

"Master, please get some sleep early. Once the enemy has settled down for the night, we'll set the traps."

"Marie-san, I leave the rest to you."

The Dungeon Master withdrew to its room.

"Rāja and the knight order launch the all-out attack before dawn, at first light. The attack begins at four-ten. Be in position by four."

The hour when the sky brightens somewhat, owing to the season, the prime-meridian setting, the rotational period, the latitude, and the tilt of the axis.

"Marie, no night raid?"

"Rāja, at night, if even part of the enemy escapes, we can't pursue. The only one of us with night vision is Haruna. None of the knight order can see in the dark."

In truth, horse-beastfolk too have night vision to some degree.

"Mint, watch from the Core Room and direct the self-defense corps to set the rockets' aim. Sapien-sensei and Anne, you're rear support. If there are wounded, please see to them. That's all. Dismissed."

[Core Room]

The great baggage train kept straggling into the main camp until well after dark. It was quite late at night before the bivouac settled down to sleep.

"Well then. The usual pit trap again, is it."

"It's the surest method, after all. I did consider another way, burying dungeon-structure walls underground and heaving them all up at once to pen the enemy in, but raising walls with dungeon energy takes time, and there'd be a risk of letting them escape, so I dropped it."

"First we designate the ground under the bivouac as dungeon structure."

"Please designate it with a little margin to spare. So that no one can get away."

"Leave the pillar sections in place and recover the earth and rubble underneath."

"If we had dungeon monsters dig the hole we could save energy, but I can't summon a giant mole or a giant ant, and I can't find any fox-beastfolk either. It can't be helped."

"In short, it's the top-down construction method. Dungeon structure has strength to it, so we need only the bare minimum of support pillars, and no shoring."

"So they can't escape by using a handcart as a foothold, make it at least seven or eight meters deep."

"A big job. What do we do with the earth we recover?"

"We'll use it later to fill in the inside of the wall."

"And then we line the bottom of the cavity with books and newspapers, and it's done. That was it, wasn't it."

"With a pit trap this size, there's a danger the newspaper gets buried in the ground surface as it falls and doesn't catch fire properly, so I'd like to pour in gasoline too, but no library these days uses gasoline. Instead I'll mix some oil and aluminum powder into the ammonium-nitrate fertilizer to make it easier to set ablaze."