Exact plans were decided roughly halfway there, when their numbers were clear. In addition to Jeralt's Mercenaries, many of the Black Eagles that could come brought soldiers from their houses; they had more than enough power to get through Myrddin, with smaller forces branching off and attacking any other bridges so their retreat was fully secured.
When the Great Bridge was in sight, the army paused and Edelgard turned to face them. They weren't exactly organized—aside from the mercenaries, many of them hadn't seen many true battles—but she still gave them words of encouragement. No one here blamed her for what happened, yet she wanted to make amends for it.
"Our allies have been trapped in a siege behind this bridge," she said. The entire army—soldiers, mercenaries, and mages—fell silent out of respect. "To say we are retaking the Great Bridge implies we once held it; by the end of the day, however, that will be rectified."
There were some cheers as they agreed. She paused for a moment, casting glances at both Jeralt for the mercenary's readiness and Hubert for Thales's mages; when both nodded, Edelgard looked back towards the army.
"We move on, then! If you find yourself in trouble, retreat back to this side of the bridge."
Another second, and she faced the bridge again. The army moved around her and towards the bridge, with only a few staying behind. They moved forward as the soldiers ahead of them made more progress; they still fought, but not a much as the others. Hubert was still wary to let Edelgard too deep among the mages, even with someone watching her—she knew Monica felt the same, and oddly Byleth seemed to agree.
Defending the bridge was Gloucester soldiers, mixed with some troops from house Phlegathon. The latter seemed particularly indecisive; one report said they fought for the Alliance, another said they attacked Gloucester soldiers, then they went back to fighting the Empire. Rather shortly, all it did was make neither side attack them—without any aggressors, they remained in place or retreated to the Alliance's side of the bridge.
Among Gloucester's forces were both Count Gloucester and Lorenz—neither father nor son made any attempt to hide their presence, but they remained fairly deep in enemy ranks. As the Imperial army continued, it seemed that those defending the Great Bridge had been asked to retreat as well.
Gloucester soldiers fought rather valiantly, but they were outnumbered. Considering the efforts put into recruitment during her time at the academy, Edelgard imagined that most battles would have that in their favor. On the matter of training or skill, Gloucester seemed more uniform in their strength—the Imperial army varied, roughly half of them being former students, but they had outliers like Byleth and any of the Black Eagles that had Crests.
Steadily, the Imperial army made progress across the bridge and to the other side. Those farther ahead encountered Count Gloucester and Lorenz; the latter had gone into the fighting while his father commanded the rest of the troops.
Lorenz weaved through enough Imperial soldiers for Edelgard to personally see him; his loud proclamation upon meeting with his family's soldiers either seemed to bolster their spirits or went unnoticed, much like it had at the academy. She always found it impractical at best, although she was more familiar with Ferdinand's similar announcements.
One of her soldiers reported that Count Gloucester fully engaged those closest to him; not very long after, Lorenz retreated. Edelgard didn't give any order to pursue. She was curious to see how they would address the situation after Myrddin was captured.
A majority of Thales's mages disappeared—not so much injured as bored, she assumed—after two hours, and as a result Edelgard was allowed a bit more movement. The battle was nearing an end at that point, but she was still able to assist anyone closer to the back; in some cases, soldiers retreated with grim acknowledgment that they couldn't fight her.
Nearing three hours, Count Gloucester retreated and every single soldier followed after him; those from house Phlegathon hastily swore allegiance to the Empire, in contrast with the initial agreement to comply, and were promptly sent on their way.
Edelgard remained on the bridge itself, assessing any damages and deciding who would stay behind to keep it. Hubert briefly left to follow Gloucester's soldiers—not to attack but to see if they would be willing to stand down—and Ferdinand replaced him. When Hubert returned, Lorenz followed behind him without any weapons.
Lorenz offered a bow. "I would like a chance to speak with you, Edelgard, if I may."
"Go ahead," she replied evenly.
"Thank you." He rose, not quite surprised but still unshaken—almost arrogant, but not disrespectful. "My father was presented with this scheme when the Empire first declared war against the Central Church; he accepted in order to preserve the common folk's livelihoods, as any noble should. He knew the risks involved and accepted them for the greater good of the people."
"That would have been the best option," Ferdinand agreed, still standing near Edelgard's left. "Compliance with the Empire would greatly reduce casualties on both sides."
"That being said," Edelgard added, "Is Count Gloucester willing to change his allegiances?"
"My father has opted to step down from his position, leaving me—Lorenz Hellman Gloucester—as his successor and carrier of his former title," Lorenz explained after a moment's pause. With another bow, he added, "All that to say, then, that yes. House Gloucester and all soldiers therein agree to fight for the Empire and its cause. Simply give the order, and we will not simply comply but battle for victory when required."
Edelgard nodded, and glanced towards Hubert. "Make any necessary arrangements."
They both understood that among those 'arrangements' would be to ensure they were genuine. Edelgard wouldn't take any more chances.
Hubert bowed, then left with Lorenz. A formal causality report came later—less than a dozen soldiers were killed on either side, most retreating when they had the chance—along with a confirmation that no mercenary was unaccounted for. Thales's mages had not returned since their departure, and for now she decided they could wait to contact them.
She put Ferdinand in charge of the troops that remained at the bridge, and one of the smaller forces were kept within Phlegathon territory to make sure Acheron didn't try to switch sides again. The rest of the Imperial army continued marching towards where Count Bergliez was held the next day.