Serious Volume 3 spoilers ahead!

So despite starting RWBY way back when it was released, I never got around to watching Volume 3 until yesterday after my fiancée and I binge watched all 3 volumes in a day and a half. She turned to me after the Volume 3 finale and said "So what was the White Fangs objective? They let the Grimm into the city which I only assumed caused them as much trouble as those defending Beacon and the city. Then they ran away"

Then I thought that I couldn't really answer that myself so maybe I missed something. So was the entire reason they were conscripted by Cinder was so she could steal the rest of the Fall Maidens power or did they actually want to cause wanton destruction for giggles and their hatred for man before running away or did they have an actual objective that we know about in mind?