This work was originally written, some twenty years ago, as a doctoral thesis in the University of Oxford, The reason for publication after so long an interval is the growing evidence of demand for a general account of the Malatesta of Rimini based on modern research. No extended history of the Malatesta has appeared since the nineteenth century, nor has anything of the sort been published or promised in the past few years. Outside a small number of specialised articles, new information has been mainly added in writings on other, related subjects: on neighbouring states and dynasties, like the Montefeltro and Polenta, or on Romagna and the Papal State in general. Little rewriting has therefore been necessary to bring the book up to date. Only the introductory chapter, handling themes subsequently discussed in works on papal government and Romagna in the thirteenth century, has been wholly recast and cut. Otherwise the original text is essentially unaltered, and revision has been mainly confined to work of abbreviation, especially of footnotes. To facilitate this, references have been minimised and almost all authorities quoted in brief, full titles being listed in the Bibliography.

At this date acknowledgements for help received must carry an obituary note. But I am bound to recall the obligations incurred, from a very early stage, first to the late Professor E. F. Jacob, who suggested the subject (Carlo Malatesta and church unity) from which the finished study developed, and to the late Cecilia Ady, who acted as supervisor and placed at my disposal her intimate knowledge of fifteenth-century Italian political history.