Obviously pretty brief but it touches on perhaps the most important parts of ancient and medieval warfare, a bunch of peasants normally didn't wipe the floor with armies of knights and mercenaries outside a few very special cases that have been done to death and arguably shaped popular conceptions because a lot of the basic tactics that work really really well against heavy cavalry and infantry actually take a surprising amount of coordination and discipline, not something a mob usually has hence why the successful ones normally contained a good number of professional soldiers or lower tiers of nobility if not being men of means with some part in a militia or expectation of military service.
And that's before you get into what happens when artillery or even the original version of combined arms with archers and infantry and cavalry working in concert can do to an army lacking any of the above and warfare evolved constantly and rapidly based on local conditions, technology, leadership and resources across the ancient and medieval period.
Then you jump into that dread realm of economics and state building or as I like to call it "the art and process of fulfilling the quest for more money by any means imaginable"
