User blog comment:Sokatsui/What Was The Point?/@comment-5551986-20121114233501

They want to destroy the shinigami. When you are at war you like to invade a place and you tend to burn it to the ground or annex it and prepare before reinforcements show up, in this case it seems like they wanted some extra firepower (Aizen) and to weaken Soul Society (Killing well over 2000 of the roughly 3600~ soldiers in Soul Society and Steal the Bankais of several captains and incapacitate two of them) Its obvious they had to retreat considering how strong the Royal Guard are supposed to be. The quincy dont just dislike shinigami, they HATE them. The shinigami tried to exterminate all of them, their home, their friends, and their way of life. The shinigami's retribution is to suffer a similar fate. And they have accomplished just that. They put a scar on all shinigami that day, they killed the strongest shinigami (i doubt a single royal guard was stronger than Yamamoto in a 1v1 fight but maybe on the same level) think of all the soldiers killed, the captain injured and home destroyed. They accomplished their goal, i see it as the coming of the storm, next they will try to completely annihilate every shinigami. But who knows, their reasoning behind their methods is still unknown.