Awe

[Quitti]

AoE answered it well, but I'd like to also point out that there are units that are effectively immune to awe, that is, most undead have morale of 50, with few exceptions (ghouls, intelligent undead leaders). Also troops that have berserk go from their base morale -> 99 morale when they berserk, which nullifies the awe. And of course there are simply those troops that have very high morale, such as Pangaeas Maenads and their ~17 morale.