[tinkthank]

Is this an AI opponent? I ask because Jugs are sacred, and bless effects could matter.

You say the jugs are more or less alone without support?

Recruiting some foreign crossbows could do the trick, together with quite a lot of el-cheapo militia types in smallish squads spread out across the field on hold or fire so that the jugs have to come and get them. And jugs are slow. Keep a few decent priests in the back for Fanatacism. Priests should be ok since the jugs will never make it back there.
Alternatively or as a boost: Cast Incinerate, that should take quite a chunk out of them.
Actually, you probably wont even need the xbows if you have a few incinerators. Since the jugs dont have much support troops, that should do the trick.
A few Warlocks casting Paralyze might work, but Im not sure about Jug MR.
Shouldnt be too much of a problem for you. About 100 gold worth of crud Milita plus what you have should mop them up.