Is this game for me?

So I have been playing this game for about a year and I'm pretty ok at it. I mean, I know how to research and build my cities and settle but the one thing that gets me and everyone else is combat. I'm sick of seeing a Knight beat an Infantry. The last game I played I wasted an entire stack of units just to retake my city. I'm not very militaristic but I mostly focus all of my efforts on research. What is going on with this game? How can I be better at combat?
I am playing BTS Next War mod.