Well the mission I think you need double time luck. Cause not everytime you get the towers of the yellow one and then you must being lucky of the blue who don't build big towers! Normally this happen when you see the smith for Ore and not the smith for tools or the base hospital in the south of his base! That's so horrible cause you need much more time to defeat the big towers than the small once. So you can start again. You can send a thief in front of his base to see what he builds. The rest of the mission is easy. Just enlarge your territory to the yellow as fast as you can to get weapons and tools. Build smith for weapons and enough mines to grow your army faster. For food you use fish. If you are strong enough you only must destroy the blue one and the rest of yellow.