Non-Fiction

I'd go with Genghis.

One told about another Kahn warlord that took over this town in what's now southern Russia, I think.

He didn't have a huge army and the town had some kind of cavalry they couldn't deal with if they put the place under siege. So, they dug this trench across the steppe a few miles out of sight and hauled off the dirt so it couldn't be seen until it was too late. They left a few causeways across it and had some guys in the grass to show them where to cross.

Then they came riding up with enough guys to make their cavalry think they could charge and wipe them out. They let them chase them getting closer all the time and they rode right into the trench. Then all the other guys that were hiding in the grass with their horses got up and helped the others slaughter them.

Then they surrounded the place and forced them to surrender. That was diabolical.