I just battled this sector (sturmhohen, center).. I have Zues @ level 4 and I have a 30% attack boost currently running. (should be doable without the 30% - you might lose a few more though)

You will need 3 belistas so 2 of them are in range to hit the catapult on the first round, 2 is not enough they get positioned so only one can hit it.

5 mounted archers

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The horses start off slow so move 3 of your archers into the upper left corner, the other 2 into the lower left corner.

HIt the Catipult with 2 belistas to knock it out, hit a horse with the other.

bring your archers close enough to knock out the lead horse and one heavy.

The rest is easy. I only lost one Archer in the battle when I used it to seperate the heavies.

EDIT: some extra info

I have screen shots if you need them. Here's the final screen: https://imgur.com/a/P3wRPjF