Byleth declared the next war meeting the day after Claude returned. "First of all," she said once everyone was there, "I would like to thank King Dimitri for agreeing to fight alongside us. I would also like to say, however, that I'm a bit disappointed in the lack of communication between me and the other commanders." As she said it, she specifically looked at Claude and Seteth. "We lost roughly a dozen soldiers altogether, who died at Gronder Field trying to strike down Emperor Edelgard."

"I didn't think they'd be killed," Claude said apologetically. "Even then, they knew it was a possibility. They didn't die in vain, either—I heard Edelgard was wounded."

Dimitri nodded, "That's true; I saw it myself. The worst one was just below the heart, and she was saved only by cowardice."

"It was a huge blow to the Empire," Seteth agreed. "Many people saw her as invincible until then. While she's still sending out factions, she can't go out into any battles herself; this makes our job considerably easier."

"For the whole month, I've been preparing our forces," Byleth said. "I propose that we take Fort Merceus, so we have a foothold in the Empire. From there, we can go straight to Enbarr."

"No opposition here, Teach," Claude replied. The rest of the council gave a murmur or nod of agreement. "I even have an idea on how we can get inside. How soon can we march?"

"As early as tomorrow morning," Byleth said. "We can still make it there by the end of the month."

"Perfect," Claude said. "I brought plenty of Alliance might back with me; if Dimitri's willing to pitch in, we could have three armies under one banner. That'll send the Empire running!"

"Don't get too excited," Byleth warned. "Our victory may be short lived."

Claude stayed silent for a few seconds. "How so?"

"Those who slither in the dark," Byleth said simply. "I've mentioned the phrase to Dimitri before. It's a name for an organization—one that isn't anyone's true ally. For now, I believe it holds the Empire's cooperation; but I'm not sure if the details. It's possible that they'll attack the fortress after our victory, and they may be present while we fight."

"I'll tell the soldiers to look out for them while we march," Seteth decided. Byleth nodded her thanks, and the meeting was soon brought to a close.

…

As predicted, they made it to Fort Merceus before the end of the month. Before they could begin an attack, however, they need to infiltrate it; for the second time in Byleth's memory, the impregnable fortress was broken into.

After receiving a single that the spies had disarmed most guards, Byleth led a faction of Knights inside. Behind her, Seteth led another faction of Knights, fit for flight; Claude led the previous Golden Deer and a faction of Alliance soldiers; and Dimitri led the previous Blue Lions and a faction of Kingdom soldiers.

Byleth's faction prioritized in getting her to the enemy general. It was the Death Knight, just as she recalled. He was watching the battle, almost with a disappointed look on his face. He didn't seem to enjoy the battle; but Byleth wasn't there to entertain anyone.

Her faction dispersed as she got closer, to the point where she was the only one facing the Death Knight. When he noticed her, he smiled, raising his weapon.

"I see that you're stronger now," the Death Knight said. "Don't hold back; I'm looking forward to this!"

He attacked Byleth, but she battled him enough times to know how he fought. Though she still loathed it, she focused on attacking the horse he was riding on; after the animal took enough blows, the Death Knight was forced to fight dismounted and lost his advantage.

After a bit more fighting, Byleth finally got him to his knees. Unlike the other generals, she couldn't simply disarm him—being the third Imperial she fought, he may have been informed about her fighting style. Byleth knew that she had at least one cut on her; it just meant she had to ask Flayn to use a bit of healing magic on her.

"So…you have me on my knees," the Death Knight mused. "What will you do now? Will you let the sword fall? Or will you exercise what seems to be your new morals?"

To show her answer, Byleth picked up the Death Knight's weapon and lowered her own.
"Pity, then?" The Death Knight asked, humming. "Vexing. I was hoping for a battle to the death, but it would be disrespectful of me to end my own life in wake of defeat."

He stood, looking at his wounded horse. "I'll consider myself defeated; but I won't retreat until most of my soldiers are defeated as well."

"You'd best prepare to leave, then," Byleth replied coolly. She knew that most of the Imperial soldiers were already disarmed, rendered useless. She pulled out a letter, handing it to the Death Knight. "When you return to Enbarr, give this to Edelgard."

The Death Knight took the letter, looking over the battlefield. Imperial soldiers were already beginning to flock to their general for orders; as Byleth turned to leave, she heard him give them a command: "We will retreat. Make sure you don't leave any other ally soldiers behind."

Byleth anxiously went about her post-battle tasks. She warned everyone of an attack from those who slither in the dark, just in case; but nothing happened. No javelins of light destroyed the fortress, and no masked mages were seen. Fort Merceus was, as soon as the Imperial soldiers left, in the Church's possession—and nothing stood in the way of that.