Also, Caesilinus is huge and there are parts that are fortified. I am ruling 60% of the mortal population dead, as efforts were concentrated on gates, walls and strategic points like the temple. The poorer and merchant quarters are way more intact. There's a huge mortal population there and while they can't put up a fight for long, they can certainly last longer than a day. 

They can declare victory, but there's lots of 'mopping up' to do in there.