And also note that Cheniérs accusation of 'we are attacking because we are ready now' is baseless. Riombara had had their regions repaired and RC's constructed roughly 2-3 months before the war began. during these 2-3 months Enweil was far more beset by rogues and still suffering from the invasion than we were. Riombara did /aid/ Enweil during that time - and Enweil did grow considerable in strength. Riombara went to war because of our alliance with Old Grehk, Thalmarkin and Nothoi - they wanted to prevent Enweil from aiding Fronen and asked us to do that. The old enmity between Riombara and Enweil was simply an additional motivation.
How is that even relevant though, it is sound strategy to seek peace when you are unprepared and to fight when you have the advantage. Regardless of if Cheniér is right or wrong in his accusation, I fail to see how the action would be in any way unacceptable or not in the spirit of the game.
