Subjugation of the Blight Dragon

The Subjugation of the Blight Dragon (邪龍討滅戦) was a battle that took place in Picoutatte following Stride's challenge to the Sword Demon after he kidnapped the Sword Saint, Theresia van Astrea. The battle ended up being the final one in a series of incursions against the Kingdom, made by Stride Vollachia and his men. Occurring between 38 and 39 years before Natsuki Subaru's arrival in the Kingdom of Lugunica, and in the year following the conclusion of the Demi-Human War, a subjugation force of 1000 soldiers and knights strong was dispatched to Picoutatte under the command of Bordeaux Zellgef to defeat Stride and rescue the Sword Saint.

Before the subjugation arrived in Picoutatte, Stride Vollachia summoned the Black Dragon Valgren and put it under his control. As the Kingdom's subjugation force approached Picoutatte, Stride made Valgren unleash its breath of devastation at the force, striking a devastating first blow. The Kingdom's forces quickly recuperated and pressed on into the city, where they were greeted by Stride's second line of defense, the magic circles he'd instated around the city to deprive people of their Divine Protections, and make it so that the Divine Dragon Volcanica couldn't be summoned. Regardless of that, the force pushed in and was met with Stride's final line of defense; all of the citizens of Picoutatte had been put under the control of Melinda's Evil Eye and were commanded to attack the force. This line of defense was then bolstered by the Eight Arms and one of the Shinobi turning up to fight them. Despite sustaining heavy casualties during the fighting, they were able to surmount these obstacles and gain a decisive initial victory.

The tide of battle then turned towards fighting the Black Dragon itself, who'd fallen out of Stride's control and subsequently eaten its master. In death, Stride's soul managed to take control of Valgren and unleashed more destruction upon the city. Wilhelm and Grimm fought the Dragon and were able to heavily wound it and bought them time until the Divine Dragon arrived, having been summoned by King Gionis Lugunica after they'd gotten rid of the Magic Circles. Volcanica made short work of Valgren and healed everyone who was still alive, leading to the total victory of the Kingdom.

Though the Kingdom took casualties, it proved to be quintessential to reaffirming people's faith in the covenant the Kingdom holds with Volcanica and resulted in the Kingdom gaining peace and prosperity for a while.

Prelude
A short time after the Demi-Human War ended, Stride Vollachia had set his eyes on the Kingdom as part of the show he wanted to create. His incursions against the Kingdom had resulted in Veltol Astrea being left disabled as well as countless other damages. His transgressions reached a boiling point when he cursed Carol Remendis and made her kill Veltol before the both of them made off with the Sword Saint, Theresia van Astrea.

Wilhelm, who'd already been trying to track Stride down, was informed of those events by Bordeaux. He found out from Tishua, who'd been made a mouthpiece by Stride using his curse rings, that Stride was awaiting them in Picoutatte. As a result, Bordeaux quickly rallied a subjugation force together which numbered approximately 1000 strong. The subjugation force consisted of soldiers and knights who revered Theresia for her role in ending almost a decade-long Civil War. The force also included the Zellgef Squadron, now commanded by Wilhelm, as well as Roswaal J Mathers. The force set out from the Royal Capital and rushed towards Picoutatte.

Battle
Prior to the arrival of the Kingdom's Subjugation Force, Stride made his preparations by getting Melinda to find people with Divine Protections to be sacrificed for the purpose of summoning the Black Dragon. As well as that, he instated his Magic Circles around the city so that the area there would be cut off from the world, meaning that Divine Protections would stop working there, as well as disabling the "magical alert syste" set up by the Divine Dragon, which would notify him in case of an attack. Meanwhile, Melinda helped set up the defenses by using her Evil Eyes to control all the citizens of Picoutatte, turning them into a swarm to be launched against the Kingdom's Forces. Finally, Stride ordered Carol to kill the sacrifices with his Dragon Fang, and completed the process of summoning the Black Dragon Valgren.

As the Kingdom's Subjugation Force approached the gates of Picoutatte, they were met by a head on volley of flame from Valgren's breath. This devastating pre-emptive blow caused serious damage to their forces, killing many and injuring many more. Despite that, the Kingdom's Forces managed to rally their strengths again and pressed on into the city after sending their injured back to nearby towns.

The rallied forces pressed into the city, and were met by the effects of the Magic Circles Stride had implanted. As a result, they dismounted from their Dragon Carriages and continued on foot. However, they were soon met by the swarm of citizens, Melinda was controlling with her Evil Eyes. Their offensive battle quickly turned to a defensive one so that they weren't crushed in the stampede. The Kingdom's Forces tried to defend themselves against the swarm without killing any of the citizens, however reinforcements soon arrived from Stride's faction in the form of one of the Twin Shura. Raizo quickly cut his way through the Kingdom's defensive formation, attacking the trapped Knights from behind, threatening to collapse their line. His challenge was quickly met by Wilhelm, and then Roswaal, however, Vollachia's strongest warrior quickly came to bolster the Stride faction's defenses. In the confusion, Raizo was able to use his ability to transport Grimm Fauzen and Roswaal to the Spire rooftop where Stride was waiting at with Valgren above.

Battle on the Streets of Picoutatte
Back on the streets of Picoutatte, the weakening Royal Forces continued to hold their defensive line against the controlled citizens whilst Wilhelm fought Kurgan and Bordeaux fought Raizo. The tide of battle started to turn when Bordeaux, though sustaining heavy injuries, defeated Raizo. Wilhelm, in turn, managed to defeat Kurgan, leaving him mortally wounded as the citizens of Picoutatte began to come back to their senses thanks to Melinda's Evil Eye being defeated by Theresia.

Battle on the Spire Rooftop
Taking place simultaneously with the battle in Picoutatte, Roswaal fought against the other Twin Shura whilst the cursed Carol was forced to fight against her lover, Grimm. Contrary to expectations, Grimm was able to hold his ground, so Stride commanded Shasuke to kill Carol. However, he was thwarted by Roswaal who sacrificed herself for her friend. The tide of battle changed after this, with Grimm causing Stride to summon his Yang Sword Vollachia, which ultimately led to him being forced to cut his own left arm off, losing half of his curse rings and as a result, control on Carol and Valgren. The ensuing fight led to both his, Melinda and Shasuke's death.

The Subjugation of Valgren
In death, Stride's soul took control of Valgren, and made him unleash its fiery breath down at the streets of the prematurely celebrating Royal Forces. Heavy losses were incurred amongst the Subjugation Force and the Picoutatte citizens. Wilhelm and Grimm challenged the Dragon, and were successfully able to wound it. However, the tide of battle shifted completely in their favour when Gionis Lugunica stirred, having been able to use the help of Valga Cromwell to destroy the Magic Circles that prevented him from calling for Volcanica's assistance. As a result, Volcanica appeared and destroyed Valgren and healed the world around them of their wounds and the dragonfire.

Aftermath
The battle was a major victory for the Lugunican military, despite incurring heavy losses among their forces and the non-combatants of the city. Volcanica's appearance reaffirmed Lugunica's might due to the covenant binding them, reaffirming itself as a deterrence to any enemy invaders.

Furthermore, the victory allowed them to seize the political upper-hand with their negotiations for compensation and culpability with the Vollachia Empire, extraditing their political prisoner Kurgan back to the Empire in the hope of trying to get them to acknowledge Stride's existence.