The son of a landowner from Rosenthal in Kassel studied after high school from 1887 /88 the University of Giessen history, classical philology and geography. In the Three Emperors year he became a member of the Corps Teutonia casting. As Inactive he moved in 1889 to the University of Berlin, where included, among others, Theodor Mommsen, Otto Hirschfeld, Hermann Diels and John Vahlen his teachers. In 1891 he was at Hirschfeld with a study of the Roman citizens in the provinces ( De Romanis civibus in provinciis imperii consistentibus ) Dr. phil. doctorate. He first worked as a school teacher in casting and habilitated in 1898, the Celtic and Germanic territories of the Roman Empire. In the following years he taught at the University of Giessen as a lecturer.
In 1902, Kornemann as an adjunct professor at the University of Tübingen, where he studied a total of sixteen years and taught. From 1907 he worked at the city's Department of Ancient History as a full professor. In 1918 he accepted an appointment as successor to Walter Otto to the Chair of Ancient History at the University of Breslau, where he remained until his retirement in 1936. In 1924 he resigned from his corps. 1926/27, he was rector of the university.
In retirement, he moved to Munich, where he took over in 1945 the last time a lecture series after the end of World War II. Since 1942 he was a regular member of the Bavarian Academy of Sciences.
For Kornemann was during his active career as a university teacher always teaching before the research in the first place. However, he wrote some historical monographs, especially on areas of Roman history. For Alfred Gercke and Edward North, introduction to the science of antiquity, he steered the sub-band at Empire. A central point in his research took the closely following Mommsen work on the Roman municipal system. He wrote, among other things, the extensive articles on the lemmas colonia and municipium in Pauly Realencyclopädie of classical archeology. In addition, Kornemann dealt with the ancient Italian Constitutional History and Late Antiquity and operational research on the ancient ruler cult. His studies on the Monumentum Ancyranum, however, postulate the layering of text, find until today little supporters.
He also dedicated the great women of antiquity a monographic consideration, but which is due to their tendency to platitudes and often uncritical acceptance of ancient source statements of rather low scientific value. However, a larger public Kornemann primarily for his two-volume History of Rome known, published 1938-1977 with the Stuttgart - Kröner Verlag in seven editions, and especially among students has long been popular. Theodor Mommsen, following the example set, the representation contains plastic, updated value judgments about the people involved. Admiring stood Kornemann, as Mommsen, in particular the figure Gaius Julius Caesar opposite; but also Augustus he praised as brilliant statesman. Kornemanns representation has long been the most popular German -language representation of Roman history; in their assessment of the past, but it is the spirit of the times closely connected and therefore of ethnic - nationalist ideology not free. So were the ancient Germanic Kornemann for the direct ancestors of the Germans; correspondingly positive they were drawn. In other respects, however Kornemann was ahead of his time by about 476 (as well as the present research ) attributed little importance to the year and the end of antiquity rather in the 7th century ansetzte.
Many of his source historical studies he published in the co-founded and edited his own magazine Klio, which is still one of the most significant ancient history trade journals.
- The new Livy Epitome of Oxyrhynchus. Text and investigations ( = Klio. Contributions to ancient history. Supplement 2, ISSN 0075-6334 ). Dieterich, Leipzig 1904 ( Neudruck. Scientia Aalen 1963).
- Mausoleum and Gestae of Augustus. Teubner, Leipzig et al 1921.
- With Julius Beloch: Roman History ( = introduction to the ancient science Vol 3, Issue 2. ). Teubner, Leipzig et al 1923.
- From ancient state. Speech given at the beginning of the Rector on October 15, 1926 ( = Wroclaw University of speeches. Issue 1, ZDB - ID 846887-4 ). Ferdinand Hirt, Wroclaw 1926.
- The position of women in the pre-Greek Mediterranean culture ( = Middle East and Ancient. Vol. 4, ZDB - ID 536323-8 ). C. Winter, Heidelberg, 1927.
- Government and business. Lecture, held in the Commerce and Industry Chamber of Breslau on February 14, 1929 ( = headings of Commerce and Industry Chamber of Wroclaw. Vol.13, ZDB - ID 638066-9 ). M. & H. Marcus, Wroclaw 1929.
- New documents for laconic imperial cult ( = Proceedings of the Silesian Society for patriotic culture. Issue 1, ZDB - ID 501662-9 ). M. & H. Marcus, Wroclaw 1929.
- Doppelprinzipat and division of the kingdom in the Roman Empire. Teubner, Leipzig, among others 1930 ( Nachdruck. Bouma 's Boekhuis, Groningen 1968).
- States, nations, men. From the history of antiquity ( = The legacy of the ancients. 2 series, vol 24, ZDB - ID 527990-2 ). Dieterich, Leipzig 1934.
- The invisible frontiers of the Roman Empire ( = Publications of the Hungarian National Committee for international intellectual co-operation. Vol. 2, ZDB - ID 2676350-3 ). Hungarian Academy of Sciences, Budapest, 1934.
- Augustus. The man and his work. ( In the light of the German Research). Lecture ( = Breslauer Historical researches. Vol. 4, ZDB - ID 538197-6 ). Priebatsch 's bookstore, Wroclaw 1937 ( Neudruck. Scientia Aalen 1982, ISBN 3- 511-07004 -X).
- Roman history. 2 vols. Kröner, Stuttgart 1938-1939 ( various issues); Volume 1: The Period of Republic ( = Kroner pocket edition Vol 132, ZDB - ID 986558-5. );
- Volume 2: The Empire ( = Kroner pocket edition Vol 133. ).
- Volume 1: Up to the battle of Actium (31 BC). 1948;
- Volume 2: From Augustus to the victory of the Arabs. In 1949.