German historian; born at Gnesen, province of Posen, Prussia, Feb. 2, 1836; son of Joseph Ḥayyim Caro. After several years of diligent study at the universities of Berlin and Leipsic, he attracted considerable attention by his work, "Das Interregnum Polens im Jahr 1586, oder die Häuser Zborowski und Zamojski, "Gotha, 1861; and was immediately entrusted with the continuation of Röppel's history of Poland in the series of "Geschichten der Europäischen Staaten," edited by Heeren and Ukert, and published at Gotha. Jacob Caro contributed vols. ii.-v. (1863-88) of this monumental work.
Before publishing the results of his research he undertook several extensive journeys through Galicia and the south of Russia, and upon his return to Germany in 1863 was appointed privat-docent at the University of Jena. Shortly afterward, at the invitation of the grand duchess Helena of Russia, he accompanied her on her travels, and was for some time attached to her suite at St. Petersburg. Later he was promoted to the position of assistant professor at the University of Jena; and in 1869 was called by the University of Breslau to fill a special chair of history. Since 1882 he has occupied the position of professor at that institution.
His reputation is based chiefly on his researches in the history of Poland. Among his works, besides those already mentioned, are: "Liber Cancellariæ Stanislai Ciolek: : Ein Formelbuch der Polnischen Königskanzlei aus der Zeit der Hussitischen Bewegung," 2 vols., Vienna, 1871-74; "Aus der Kanzlei Kaiser Siegmunds," Vienna, 1879; "Beata und Halszka: Eine Polnisch-Russische Geschichte aus dem 16. Jahrh.," Breslau, 1880; "Lessing und Swift: Studien über Nathan den Weisen," Jena, 1869; "Das Bündnis zu Canterbury: Eine Episode aus der Geschichte des Konstanzer Konzils," Gotha, 1880; "Ueber eine Reformationsschrift des 15. Jahrh.," Danzig, 1882; "Johannes Longinus: Ein Beitrag zur Litteraturgeschichte," Jena, 1863; "Catherina II. von Russland," Breslau, 1876.
- La Grande Encyclopédie;
- Brockhaus, Konversations-Lexikon, 14th ed.;
- Meyers, Konversations-Lexikon, 5th ed.;
- Gubernatis, Dictionnaire International des Ecrivains du Jour;
- Vapereau, Dictionnaire Universel des Contemporains.