Heroes of Might and Magic: can't get out of town

I am playing a scenario in Heroes of Might & Magic IV ("A Tale of Two Enemies") at the Novice level in which I start in a town in one corner of the map and there is an opponent I have to defeat at the other corner. However, I cannot get out of my town. Both exits are guarded by Waspworts which are much higher level creatures than me and my army, so they crush me no problem if I challenge them.

I have done everything the town area has to offer (captured saw mills, picked up gems, etc).

How can I level up to defeat the Waspworts and progress further?

Solution 1:

I finally figured it out. There is a third way out of the area in addition to the two guarded by waspworts:

Even though the wall looks solid, the circled area actually has a gate in it and you can ride right through.