Hi, I have stormed the church tower now several times after virtually wiping out the germans and got US victories whilst playing this scenario. Maybe I had an advantage because I designed it and knew what to expect from the AI. Anyway, it can be done but I am not going to put a walkthrough here as a spoiler. The Germans in this scenario are full of surprises and it should stay that way for anyone who tries to take them on.
My advice is just read the scenario instructions (your orders), rethink your tactics and don't lower your guard. tread carefully before launching your full scale attack but don't leave it so late either.
If you fail again, next time you will be court martialled.