As a patron saint of lawyers, St Fidelis of Sigmaringen (1577–1622) must be amongst the busiest and most frustrated intercessors in heaven. Yet, as Matthias Emil Ilg shows in his fascinating and exhaustive study, those promoting Fidelis's cult on earth were equally industrious and laboured as often in vain. A Capuchin missionary and preacher, Fidelis was canonised in 1746, more than a hundred years after his death at the hands of Calvinist soldiers in the midst of the violence of the Thirty Years’ War. Yet, as Ilg observed, the fact that Fidelis was canonised at all made him unique: not only was he the first and only early modern Catholic martyr to receive that honour during that period, but at a time when canonisation was dominated by Spaniards and Italians, he was the first German to receive the honour as well. It is not only the delay, then, but especially Fidelis's eventual success that requires explanation. Ilg's two-volume study of the Fidelis cult takes the reader on a journey with many ups and downs, ending with Fidelis's beatification in 1729. Stakeholders include, inevitably, Fidelis's own order and the princes of Hohenzollern-Sigmaringen, but they also encompassed Catholic soldiers, imbued with a similar militant zeal. His cause was also taken up by the Austrian Habsburgs and it was fittingly tied to the Congregation for the Propagation of the Faith (Propaganda Fide), founded in the year of Fidelis's death. Yet, the cult faltered for the first time in the 1640s, precisely because of its adherents being too closely associated with the militaristic Habsburgs. A dearth of miracles throughout the 1650s and 1660s (Ilg includes a complete inventory) suggests that the cult might have died a slow death, had it not been revived in 1674 by Lucianus Montifontanus’ almost 600-page Vita of the martyr. Twenty years later the cult nearly crossed the finishing line, but the consultors of the Congregation of Rites rejected the cause for lack of eye-witness evidence of Fidelis's death. (In a letter to Montifontanus, the Capuchin postulators denounced the consultors as enemies of all canonisations.) Ilg persuasively attributes the sudden success of the cult a generation later (Montifontanus would not live to see it) to a shift in papal allegiances away from France and towards Austria. The same decade that witnessed Fidelis's success also saw the elevation of Vienna to an archbishopric and the canonisation of the fourteenth-century Bohemian martyr John of Nepomuk. There is much in Ilg's account that deserves high praise but it needs to be excavated from underneath the layers of descriptive source commentary expected of a German PhD dissertation. A shorter version could have made a good companion to Clare Copeland's magisterial study of the canonisation of Maria Maddalena de’ Pazzi. The fact that Ilg was able to write this study without consulting Roman archives elicits a certain measure of admiration but remains a shortcoming. However amazing the postulators’ correspondence back home, this study misses the Roman perspective on the same events. Not that Ilg's study should be any longer than it already is.