Today was not a good day to be around Argantan. His guards who knew him well could see him seethe even if we have a man who could hide his emotions well enough. Henry de Stonee had fled and the Councilate had refused him. Altogether nothing had been lost but nothing had been gained either. 
Henry De Stonee had frustrated him in particular, he had given the man large swathes of land,protection,providers, offered him a position of as honorary member of the ruling warrior class, given his sons the opportunity to become great men of Lascaux and offered Henry the third most important post In the land. He simply could not understand the man’s refusal . Could he not see that he was just ensuring the by giving him some security? Nevermind it did little good to dwell on the past. More men would come and next time he would try a softer approach, Argantan was not just a soldier but a practical man humility served its causes. This lesson would be learnt and next time an opportunity to advance his Nation’s economy would arise he would have to be more welcoming. 
Lascaux had little industry and her mines were dry yet her fields were plentiful. This is where Lascaux would have to make money for now. Argantan would invest heavily in modernizing agriculture. New plots of land would be turned into farms, newer more modern tools would be sent to existing farms and different varieties of crop seeds would be purchased from abroad. Messengers would be sent out to invite agricultural experts to come to Lascaux where they would be given well paid employment and benefits in return for their services. Considering how De Stonee had published a public letter he decided that it might be wise to also include a guarantee of safe-passage in an out of Lascaux.

The Councilate had been polite enough and they had mentioned the possibility of future opportunities for now this would have to suffice from them. Traditionally such a refusal would have been followed up by a series of hamlets set on fire and farms sowed with salt before another more expensive offer of protection was sent. However the Conciliate of Arbasses had reminded him of an important lesson in diplomacy and he was willing to forgive their refusal. When strength of arms was the only card you had to play never negotiate with people who are in a position of strength. The weaker or more desperate a party is the more likely they are to accept. With this in mind Argantan quickly wrote a letter, this time more polite than the last offering the services and friendship of Lascaux in exchange for economic guidance and expertise to a more desperate leader. The letter would go west.

TLDR:
Argantan dosen’t understand how non-military human beings don’t respond to violence
He invites argicultural experts from any nation to come to Lascaux and bring their expertise to the field (Pun intended) He offers a generous package to make up for the bad rep the Henry de Stonee fiasco ha given him.
Lascaux Independently invests 10 Billion in it’ own agriculture ($5Billion immediately on non-technical improvement and $5 Billion more are set aside for when the experts arrive)
A letter is sent west to a more desperate nation offering friendship offering military support and exchange for economic technical assistance and guidance. The deal will include a trade agreement.(Check your messages)