It's mandatory now to have your barracks at level 15 in chapter 5 now it is not necessary at the time and still not.what about the needles? Did you forget those or I am not able to see them?
needles increases barracks and also with needles at 11 minimum, you will get a lot stronger archers.
And if you rush to fast through chapters, you will never get the balance with upgrading wonders.
I know that, because I rushed a city from chapter 4 to chapter 14 and now I am still in this chapter since 1 year to get all other stuff done.