I'm not sure I could have pulled it off. It's exactly the kind of situation where you need to build a lot of "Copetolei" (presumably a specific unit or strategy).
It looks like a throwaway match – the guy initially asked for both an automated and a non-automated game, attacked with Solmyr and a cannon, said he'd have to fight for more than an hour, and then we loaded the game. He executed it completely differently (I observed the whole thing from the overview) and then surrendered on the same turn.