The Godswar
The Godswar coincided with the Targotian Cataclysm (known elsewhere by other names, e.g. 'The Wrath' in Ekkac, and 'the Great Breaking' in Akeaom), and together, they formed the foundational events that shaped the world of Gæðí as it exists today.
Taking place almost entirely in the remote northern 'Godlands' (the name by which the Ancient Wylden referred to the lands north of their ancient Wyld) and the nearest adjacent centers of human habitation, i.e. the ancient Wyld and the homelands of the Iona in the east, The Godswar was fought between the forces of Creation, championed by the Nostín gods led by Gáðæn Worldfather, and the forces of Kjás the Unmaker and Ísje the Frost Queen. The conflict concluded with the binding and dispersal of the Unmaker, as well as the physical binding of the Frost Queen to the mortal realm, where she remains still; bound to Icewall Glacier in Hrafnawyld, and watched with constant vigilance, yet still exceptionally powerful in her own domain.
The Conflict
Prelude
For over a thousand years, the Únðárín (OON.thow.reen), the dark gods of chaos and uncreation, had discreetly built up their strength in the distant, uninhabited northern regions of Gæðí, taking advantage of the relative inattention of the gods of creation as the latter were preoccupied with their newest labours, i.e. life and consciousness. During this time, the first Fájunn, Rúðigann and Hákke, were 'created', and from them came legions more of their kind bred over a millennium. Likewise, this period saw the creation of the immensely powerful Gáníswyrmen ('great ice wyrms' in Tallað), mightiest of the servants of Ísje.
Associated Events
This feels like the kind of conflict that doesn't end when the war does, but continues in a perpetual cycle. What are the myth structures built up around the Godswar?
You are 100% correct. The goddess Ísje (who I meant to write up during the March of 31 Tales, but she's a really, really difficult one to write) remains quite potent and powerful on Icewall Glacier in Hrafnawyld, and there are other, lesser manifestations of the Godswar's legacy to be found elsewhere. In fact, the Bloodhand Rebellion relates to one of those lesser legacies.