The Higheast Rebellion (ハイイースト動乱, Haiīsuto Dōran) was a war fought between the Dunan Republic and the Holy Kingdom of Harmonia over the territories of the former Highland Kingdom. The events of the war form part of the backstory for Suikoden III.
The Higheast Rebellion refers to the war fought between the Holy Kingdom of Harmonia and the Dunan Republic over the territories of the former Highland Kingdom that had been incorporated into the latter at the end of the Dunan Unification War.
In 472, a small riot broke out in Higheast Province, the former Highland Kingdom. Taking advantage of this unrest, Sadram, the general of Harmonia's frontier army, invaded the Dunan Republic without permission from the Harmonian government. In response, Dunan President Teresa Wisemail would dispatch Boris Wizen and Klaus Windamier to defend the country.
In addition, other veterans of the Dunan Unification War, such as the retired Chancellor Shu and Generals Viktor and Flik would rush to aid the Dunan army as it fought its defensive war. As a result, the Dunan army was able to repel the Harmonian frontier army for six months.
As the conflict drew on, the Harmonian government realised the unfavourable results a prolonged war over the region would bring and sent messengers to the Dunan Republic, recalling General Sadram and admonishing him for acting so rashly without orders. As such, the war would end with a Dunan Republic victory, and its territories intact.
- Gensosuikoden Kiwami Encyclopedia, page 337