Why did the Queen of Unaroyal destroy herself?

[multilis]

I assume that Stanley's mounts (dragons) had a higher move than any of her mounts. This may be part because of terrain, in many games it costs fliers less movement than horses to cross some terrains.

She might have been able to flee if she retreated several turns earlier. But earlier she thought she could weaken the enemy by a last stand. Now she realised the last stand would only make them stronger.