The Unification War

The Unification War (10 BU - 1 BU) was the culmination of the Erres-Wyeh tensions at the end of the previous era, which ended in the country of Erwy being founded.
The beginning of the Unification war is dated at 10BU, however some historians link it directly to the Sadantes coup in 23 BU. The power struggle and civil unrest in Wyeh, which resulted in a bloody revolution and exile of the Jasun dynasty, while decidedly significant, still required over ten years to transform into a full-scale war with the country's western neighbor.
This is partially because the balance between Erres and Wyeh was incredibly stable. Both spanned over about half of the continental mass of Dain, separated by the mountains of the Midline Range. The two major mountain passes allowed for fluid movement of resources, mostly grains and food to Wyeh and metal and sefia to Erres. However, while Erres remained for the longest time a loose net of provinces, simply tolerating the largest one as the peacekeeper and titular ruler, Wyeh slowly centralized their leadership. This led to a clear scapegoat for the Sadantes family when someone was to blame for the rising prices and increased westernization of Wyeh, including the encroachment of the Voice.
By 10 BU, the situation in Wyeh was dire. The Sadantes harshly reduced metal and sefia exports to arm the population, starving after years of drought. While this, together with increased anti-Erres rhetoric was noticed by the Erres nobility, it was mostly ignored. Thus, when the mountainside trading outposts were first overtaken by Wyeh soldiers, Erres was caught largely unawares.
Surprisingly, the assault was not as successful as it could be not due to the nobility mobilizing, but due to a band of highwaymen who for years tormented the northern mountain pass. Furious at the invasion, the Shepherd and his flock united the surrounding communities in guerilla warfare, mounting traps and assaults that halted the vanguard of the Wyeh army for weeks.
This allowed enough time for Lineos Parmes, the king of Erres, to organize a counter-offensive. With a royal decree, he ordered all his retainers to immediately follow him into the battle. Unfortunately, the nobility was slow to react. The king had very little following among the wealthiest families, and while some support for the frontlines was sent, it was out of obligation, not willingness.
By 7 BU, Sadantes and their army spilled throughout the south-east of Erres, pillaging and robbing the countryside. The northern assault was mostly stopped. Though the Shepherd and his men had to retreat after heavy losses, the local nobility managed to wipe out the invaders before they could take too much ground beyond the mountains. Stragglers were travelling south, in the direction of the main army. There, several provinces were being slowly closed off by the aggressor's troops.
King Lineos, who spent most of the war on the frontline, was in a bind. In open field, his opponent had similar numbers but technological advantage, especially now, that Erres failed to protect the mountain passes. Then, it dawned on him. The enemy was the exact opposite of him. People followed Sadantes out of fear and desperation, while he had to almost beg to get his countrymen to do what he asked. Even the war, as long as is didn't reach the western provinces, was being ignored. He had a choice: either to incite fear in others, or weaken the enemy leadership. He chose the latter.
His plan was split into two parts. First, he enlisted help of the Voice. While the organization already took an anti-war stance, the king of Erres pushed them to journey through the frontlines and to take sea journeys to Wyeh to spread the message of peace. Dressed as travelling bards, theather groups and other entertainers, without making their affiliations known, they performed their mood-altering songs for unsuspecting audiences. This was the first instance of psychological war on Dain and it made the ruling powers conscious of the Voice's true might if it ever became a threat. The song worked, though mostly among the regular people, paradoxically sowing discontent for the Sadantes and their followers.
In addition, by 4 BU, while the frontline didn't change much, Sadantes lost several of their field commanders. This was because of the small squad of experienced hunters the king's men found and hired specifically to assassinate certain targets. The king, surviving an attempt at his life himself in 6 BU, asked twenty volunteers to take out lieutenents of the Wyeh army. Guarded less than the top of the command chain, the band chipped away at small enemy camps. This lead to increased desertion and backstabbing, as ambitious soldiers wanted to obtain the freshly vacated positions, or, in some cases, create them among the leadership confusion. Rarely and after days of planning, an arrow pierced one of the tents with the Sadantes sigil, burying into bodies sleeping inside. This is how three of the six family members present on the frontlines were killed. Identities if the ten shooters were kept secret, to protect them from retibution after the Unification. One of them was Veron Teshek, later founder of the Hunters' Guild.
With the population's support and command chain's integrity failing, unable to break the stalemate, Wyeh determination dwindled. In 3 BU, a counterrevoulution occured in Wyenthal, strong enough to overthrow the Sadantes, but not confident enough to replace them in a wartime. A council of Wyeh nobility sent a letter to the Erres crown asking for inducition of the peace talks.
The last two years of the old era were spent discussing the future of the continent. What began as the meeting of the Erres royalty and ten Wyeh families, quickly became an enormous assembly, where almost every person with a claim to a land or a tiltle appeared to gain fame and more wealth in the new world order. What historians dubbed simply the Unification Council, resulted in the current geopolitical order.
First was the issue of attenuating and reversing the results of the war. The Erres provinces, held hostage by the Wyeh armies, were freed from their occupation. There was a concerted effort to imprison the remnants of the Sadantes family and their followers, however a lot of them fell victim to mob justice or fled. Hestek family was established as rulers of the old Wyeh capital, Wyental. Transit of goods was restored with expedience to appease populations on both sides of the mountain range.
Then, there was the task of ensuring a war like this would never take place again. To this end, Wyeh nobility agreed to become incorporated into Erres and to form a new country of Erwy. This change would prove to be mostly titular to Erres citizens, but as a result Wyeh underwent a series of additional structural changes, decentralizing their government and taking on Erres characteristic of self-governing provinces. The capital of Erres, now also renamed Erwy, remained the seat of power of the Parmes family. The king's role remained almost the same, though due to his involvement in the war's resolution and peace talks, his esteem grew enormously. The Erwy's crown is the final judicator of any territorial disputes, regulates trade and the spread of knowledge among the populus. Now, that contact with Zea has been made, it needs to again engage in international relations. They hope, that not only can a conflict between continents be avoided, but also that the treasures of the new lands don't reignite any dormant fires in their homeland.