This book began life as a doctoral thesis submitted to the University of Oxford in 1982. In rewriting it after four years, I have made many changes: all the chapters have, to some extent, been rearranged and rewritten; new material has been introduced and the bibliography updated; the footnotes have been reduced and I have tried to enliven the rather dull and awkward style in which I found the thesis had been written. None of these changes has altered the overall or detailed argument of the thesis and I hope that none has generated unwitting errors. I have especially altered the material of chapter 6, but remain grateful to the editors of the English Historical Review for their permission to reproduce parts of an article published in that journal in 1985.

In carrying out the original research and in revising the thesis now, many debts have been incurred, of both a professional and personal nature. I hope that, in recording those below, others not mentioned will consider themselves included in my gratitude. Greatest of all is my debt to Dr P. J. Jones, who first awakened in me an interest in Italian history, who suggested the Este as a research topic and who supervised the writing of the thesis. I owe more to his vision and trust than can be recorded here.