The subject of this biographical study is known, if at all, for the dismissively sarcastic comment passed on him, for his supposedly ludicrous self-esteem, by Aeneas Silvius Piccolomini. That the future Pope Pius ii hardly lacked self-esteem himself is well known, but the self-promoting publicity of Piccolomini was destined to achieve lasting fame through its stylistic elegance. The author of this volume has determined not to let Piccolomini have the last word, and so has turned a typically thorough German doctoral thesis into an exceedingly long book. One reason for its length is that extended passages of diplomatic correspondence are reproduced in their original Latin, or more often Italian, in the footnotes, in addition to being summarised in the German text. After many chapters, the papal conclave of 1458 is reached, in which Pius was elected and his would-be rival, Castiglione, was not. The brief remaining part of the latter's life saw him efficiently kept away from the Roman court by the new pope. Castiglione otherwise emerges as a figure incapable of making much headway against the will of his territorial ruler, Francesco Sforza of Milan, whose hold on the duchy involved unyielding control of major benefices in the state, irrespective of Roman wishes. But if Castiglione could not deliver pleasing results to the papacy in this context, he evidently could not much please the duke. For, during repeated missions as papal envoy to the emperor and other transalpine rulers whom Rome was encouraging to launch a crusade in response to the fall of Constantinople, he never delivered to Sforza the imperial investiture to legitimate the duke's exercise of power. Despite the patronage of major European prelates, Castiglione found it hard even to obtain from Sforza initial entry into a north Italian bishopric. To obtain the status of cardinal was even harder, since Sforza put other candidates ahead of him in approaches to Rome. Here the author makes good use of the work of Ilardi, which established the systematic code used at Milan to rank letters of recommendation on many fronts. The lack of authority of Castiglione as cardinal is revealed as both cause and effect of Sforza's unwillingness to find him adequate financial resources from Lombard benefices to sustain his new dignity. The author concludes with a frank assessment of the dispiriting state of the mid fifteenth-century western Church which emerges from all this, but the nature of the voluminous diplomatic exchanges reviewed here reveals hardly anything of the subject's personality. Thanks to the author's thorough work, a further study of Castiglione will probably not be needed for a long time.