I'd be very curious to know the story behind this if anyone feels like sharing. 
After the regions defected to Aurvandil, Barca demanded them back simply out of friendship and expedience, so Mendicant replied with "Well no, we're not just going to hand them over because it's easier to do that and not consider the consequences". The defecting lords all told a story of corruption and tyranny in the Republic, such as what the original Aurvandilan's had to put up with in Madina, so we decided to hear them out the lords, and demand that Barca tell us their version of the story. Considering it more important to take the honourable path over the regions rather than the expedient path based solely upon the friendship between Aurvandil and Barca, and the personal relationship held between Mendicant and other nobles of Barca. Eventually, after much talk and consideration, Aurvandil was able to conclusively determine the accusations to be true with the Barcan Ambassador only able to try and justify them as the right thing to have done. To which Aurvandil then gave them a compromise, if they make change of consequence in the realm their realm operates, to tackle the problems Aurvandil listed in their Republic then we would hand back the lands without an issue and return to the once amicable state of affairs. However, the Barcan Senate proffered nothing, but eventually offered Aurvandil a fairly meaningless extension to the treaty of Evanburg that could only really come into effect after we handed back the lands, and since then said and did nothing to further the talks.
This wouldn't be justification alone for war; however the Barcan Ambassador levied quite a few insults and dishonours against the High Sovereign, such as calling a liar, a traitor, a manipulative politician, an opportunist and so forth, and even went so far as to state that Aurvandil owes its existence to Barca and is obligated to live in a shadow of gratitude to Barca. Which didn't sit well at all, and it was made worse by the severe breach of etiquette during the talks, such as the Ambassador turning his back on the High Sovereign, snubbing him, trying to correct him, cutting him across and otherwise treating Mendicant like a mere ambassador, and not "the Highest of Sovereigns", etiquette/decorum is everything in the Aurvandilan royal court, and breaches of it are a great dishonour and slight. In response to multiple such slights, insults and dishonours, Mendicant ordered his Knight Hausos to suitably dishonour Barca in return, so the Knight Hausos (In a fairly epic Roleplay) sharpened his sword on the stones of the Barcan Senate before their Senators, which was the absolute worst form of dishonour in the eyes of Aurvandil, not just to the Senate, or Barca, but to their very peoples, honour and dignity, to which the Knight Hausos then stated that due to such dishonour Barca are now obligated to offer Aurvandil terms for war, under the threat of war and had a day to do so. Equating the war to a duel, merely fought to gain satisfaction in combat, not to win, or to expand, but for both parties to consider their honour suitably defended. This war is entirely about honour, though foreign intervention promises to force this war not to be one for satisfaction, but victory merely for victories sake, a war fought because it is a war, not for any higher purpose.
