Capítulo 425: 7.10.2 The autistic mage.

More than fear, the nobles felt disgusted when hearing about ghouls, for they are the bringer of rot and diseases and absolutely disgusting smells while generally being treated like a pest on the battlefield that can't be ignored.

They hide underground during the day and only come out at night to scavenge what remains of the dead, sometimes even dragging living people to their tunnels if there is a large population of ghouls present, where their victim would generally die and rot until ready for the ghoul consumption. 

So one or two might not be dangerous, but with enough ghouls together, they can turn into real problems for the military.

The very fact that an extermination squad was active during the day so close to the Barracks meant the population of the ghouls they had been hunting was not very low.