So, I read this manga, Kingdom, and it got me to redownload this. Naturally I decided to bash my head against the wall that is Zheng Jiang again, but this time, the later start is actually working out. I kept refusing merc contracts until I'd captured the iron mines near her start, then I took one... from Cao Cao... to go fight Lu Bu. I shoed up right when Cao Cao himself was about to assault Lu Bu's one stronghold and so collected a few thousand gold and Lu Bu's own personal spear for basically nothing. Meanwhile, Liu Bei took the city north of me, sadly, but I got another mercenary contract from Cao Cao to fight somebody who had the city straight south. Meanwhile, he was smashing the hell out of this dude everywhere else (I have no idea why Cao Cao kept hiring me, he didn't need the help), so I got a basically free city out of it. Was the guy's last province too. At which point, Lu Bu (who had joined Liu Bei) did the Lu Bu thing and snagged 4 of Liu Bei's territories in a rebellion. But I noticed he didn't have much in the way of actual armies, so I grabbed a basically-free farm province so I had everything in the commandery.
After a few turns staring across a river between the farm province and a small city with a full stack worth of Lu Bu, I decided to take a risk and moved up into Ambush stance. He took the bait. Ambush failed and I was looking a pretty dire prospect, with 0 forests to take advantage of my vanguard deployment in, a very small edge in numbers that was more or less negated by him having 2 units of heavy cav, and of course Lu Bu himself. I tried to get fancy and set up on a small island in a river, but it turns out shallow water doesn't do shit to cav charges and he ended up sweeping away basically all of my archers. Then something weird happened. He was refusing to duel Zheng Jiang, so I just had her follow him around and take potshots, and after a few of those he just sorta... went down? Like, really easily. After that it turned into a bit of a clusterfuck. Lu Zheng and her whole detachment got routed, as did most of my other units, but I'd snagged a legendary Vanguard general and gave him Lu Bu's spear, so between him and Zheng Jiang they managed to just grind out the remaining enemies like they were playing a Dynasty Warriors game. Was kind of ridiculous.
But now I've got that city of his. He sued for peace while he was besieging it, and I was low on dude, so I took the money. Now I'm just looking for my next expansion opportunity. And hopefully some more money so I can get a second army off the ground.