His biography Frederick the Great, published in 2004 and widely acclaimed, gave lasting impulses to Prussian research.
Kunisch was assistant to Friedrich Hermann Schubert at the Christian-Albrechts-Universität zu Kiel from 1963 to 1968 and at the Goethe University Frankfurt from 1968 to 1972.
Among his academic students are Hans-Wolfgang Bergerhausen, Franz Josef Burghardt, Johannes Burkhardt, Harm Klueting, Helmut Neuhaus, Andreas Pečar, Gorch Pieken, Michael Rohrschneider, Lothar Schilling, Anton Schindling, Michael Sikora, Barbara Stollberg-Rilinger and Aloys Winterling.
Under his leadership the Zeitschrift für Historische Forschung developed into the probably leading German journal for late medieval and early modern studies.
[4] An essay Über den Epochencharakter der frühen Neuzeit (On the Epochal Character of the Early Modern Period) from 1975 is considered to be the impulse for this newly developing historical sub-discipline.
[5] Kunisch, and above all his student Barbara Stollberg-Rilinger as editor, also led to a consistent opening of the journal to cultural studies topics.
The dissertation dealt with the Doppelkirche Schwarzrheindorf and the influence that Conrad III and the Archbishop of Cologne Arnold II von Wied [de] had on the construction of the building.
Using the example of a chapel house from Staufer At that time Kunisch tried "to draw an extension of the knowledge of general history from the research of an architectural legacy".
[8] In his habilitation thesis he asked about the connection between state conflicts in the 18th century and the structure of early modern statehood.
In 1986, he published a comprehensive account of absolutism, [9] Kunisch presented a multi-volume edition of the writings of Gerhard von Scharnhorst.
In November 2000 Kunisch held a conference in Berlin on the occasion of the 300th anniversary of the royal elevation of the House of Brandenburg.
[10] Kunisch achieved fame far beyond the specialist world in 2004 with a comprehensive and repeatedly published biography of the Prussian king.