If you are going to build Oxford, ALWAYS, ALWAYS, ALWAYS (Yes, it's that important to be repeated and in all caps) make sure Industrialization is your last researched tech. If you see you're going to build Oxford before getting Industrialization, switch to building a different wonder for a turn or two, and if you are going to get a new tech before building Oxford, quickly switch research to another tech. This is that important because your free tech will be Advanced Flight. This allows the building of Bombers /way/ before your opponent can build Fighters. For pretty much an entire era you'll be able to drop bombs from the sky, destroying your enemy's armies with your 108 attack veteran Flying Fortress Wings (Then again, I was playing on Warlord today, just because I can. It is a little lower on the real difficulties), killing everyone and thing that dares to stand in your way.