Krumbacher, the historian of Byzantine literature, says that the work cannot be surpassed. In these volumes Hergenröther laid here in minute detail the origins of the Byzantine Church, its development since the fourth century, and after the death of Photius until the completion of the schism in the twelfth and thirteenth centuries. While professor of canon law at Würzburg, Hergenröther published several important historico-canonical essays on such subjects as early ecclesiastical reordinations (Ester, Vierteljahrsch. f. kath. Theol., 1862), the canonical relations of the various rites in the Catholic Church (Archiv f. kath. Kirchenrecht, 1862), the politico-ecclesiastical relations of Spain and the Holy See (ibid., 1863–66), and the canon law of the Greeks to the end of the ninth century (ibid., 1870). His interest in the ecclesiastical vicissitudes of his own day was manifested by valuable essays on the States of the Church after the French Revolution (Hist.-polit. Blätter, 1859), spirit of the age (Zeitgeist) and papal sovereignty (Der Katholik, 1861), and the Franco-Sardinian Treaty (Frankfort, 1865). Among his historico-apologetic essays are his treatises on the errors condemned by the Holy See in the Encyclical (Syllabus) of 8 December 1864 (in the Chilianeum, 1865), the veneration of the Blessed Virgin in the first ten centuries of the Christian Era (Münster, 1870). He was a regular contributor of similar but briefer articles to the Würzburg periodicals, "Die katholische Wochenschrift" and the "Chilianeum". Hergenröther was constantly engaged in attempting to develop a genuine Catholic sentiment and truly Christian life among the faithful. He preached frequently, and was always a welcome speaker at the general assemblies of the German Catholic associations (Vereine; 1863–77). For the Fulda meeting of the Prussian bishops (1870) he prepared an exhaustive historical study on the spoliation of the Papal States, in which he developed at length the arguments for the temporal power of the papacy. At Munich he gained the reputation of being one of the most learned theologians on the Ultramontane side of the Infallibility question, which had begun to be discussed; and in 1868 he was sent to Rome to arrange the proceedings of the Vatican Council. Together with some other Catholics, Hergenröther deplored the attitude that certain Catholic theologians assumed from about 1860, in particular that of the celebrated historian Döllinger. The latter's work Kirche und Kirchen, Papsttum und Kirchenstaat (1861) was criticized by Hergenröther in "Der Katholik". At the Munich meeting of Catholic savants (1863),