Honestly I don't know what took them so long to just wipe us out.
Sympathy to their plight despite their crimes (as Luria saw the looting and broken negotiations)? Seeing their D'Haran allies fail them over and over. A policy of giving them time and opportunity to turn their backs on their allies who were failing them from day one and join us against their allies (or a variety of offers along similar grounds) and actually achieve their survival (probably where Fissoa is now). A specific policy to take back Barcan lands last after re-liberating else (Poryatown, Giask, Irvington, SP etc.) while we continued to give them an opportunity to save their realm. Even as we were marching into Aveston in the final assault, my character was still offering Barca terms to avoid annihilation.
