You didn't ask me, but I'm having the opposite experience you had. I've had what seemed to be unusual success in battles. If I had lost as many units as you did, I probably would have given up my attempts to finish. For example, I had something like 8 or 10 units ready to take Karakorum and it fell with the first two attacks. It did not have barracks (At least I assume it didn't since that's what production was set to when I captured it), and they had already sent several troops out toward my stronghold where they got cherrry-picked. I probably wasn't facing vets at that point. Other than capitals, most cities have fallen to diplomats instead of fighting. (Edit to add: This will likely have to change over the end of the game, so my losses may increase) I don't think I have faced any walls, and I think I've only faced two pikers so far. Anybody researching feudalism has gone straight to the top of my hit-list to minimize this factor.