[Jack Simth]

If that's it, there is something you can, maybe, do about it - army-killing spells (such as Fires From Afar ... although that won't work, as they are likely underwater....) and assasination spells (such as Earth Attack).
Spells go before the Movement phase, so they will still be in the province Ermor attacked from when the spells hit. Army-smash spells reduce the number of units, assasination spells remove the commanders, and thus keep the troops from moving (I think).

The really big problem will come in when two colossal computer players choose to fight each other somewhere you can't see them.