So, the basic game is solid! Well done. It works, and is enjoyable.
As for advancement, I might add levels you can reach where there are harder things, or a big enemy you have to defeat in X turns. Or maybe upgrades? Or maybe a win condition.
Once my army got to about 100, I could beat anything the RNG could throw at me. Army 133; Lands 13; Peasants 280; Gold 2354