One more bit from Grainger that I find very Gloranthan:
“At the end of any war, a conference was held in which peace terms were worked out. This was frequently between high advisers for each king, the meeting taking place in the main city of one of the protagonists. The negotiations were only preliminary, and peace was only actually made when the two kings involved took oaths to observe it – that is, the oaths signified the ratification of the peace terms; until that point the terms could be rejected or renegotiated.
The significance of the process, especially the oaths the kings swore, was that after the peace agreement they could not fight each other for as long as they both lived, or they would be foresworn; it also meant that when one of them died the other felt free to launch a new war.”
So with the Lunar Empire, conflict continues until the defeated ruler submits to the Red Emperor, swears the oaths of peace, and is then welcomed within the Empire, likely as a provincial ruler.