Why didn't Sauron lead the attacks?

[Agburanar]

I had another interesting thought. It's always been my suspicion that Sauron had no actual form at the end. He was embodied in the remains of the Nazgul and held together only by the power of the Great eye. I am a firm believer that the eye was somehow manifested in a huge statue in one of the highest chambers. It's just an image that appeals to me, he'd be a suitable candidate for some kind of Idolatry.