If your goal is to attack the group though you'd want to make sure they are in the village before launching an assualt. Otherwise you just put them on guard and they either flee or can prepare to launch a surprise strike, neither one are tactically advantageous to the army. And we've seen this world's armies aren't some thrown together group of uncoordinated peasants.
On the other hand, discovering your target isn't in a village (presuming that is the goal) and then ambushing them on the way is very much a sound strategy under normal circumstances, at the very least it cuts down on the numbers you face.
Now in reality I'm not sure you could ambush this group, but at the very least you get to choose the ground and limit ally help, even if for only a time.