Oliver Who?

I'm reading a book on early Quakerism and the religious and social ferment leading up to it. It covers a lot of English history very rapidly -- too much so for my comprehension. After reading this and Geo. Fox's Journal, my curiosity was piqued: so who was Cromwell and what was all the fighting about?

I found this link by the BBC that gives a short summation in several video clips that helped to answer some of those questions.

http://www.open2.net/civilwar/