After teaching at Heinrich-Heine-University Düsseldorf and Friedrich-Alexander-Universität Erlangen-Nürnberg he was Assistant (Chair of Prof. Wolfgang Altgeld) at the Historical Institute of Julius-Maximilians-Universität Würzburg.
Between 2014 and 2018 he held a tenure track position at the City University of New York, where he taught World History at Queensborough Community College, and served as the CUNY Academy's Officer for Internationalization and Global Exchange.
Jacob is editor of numerous journals and series, including Global Military Studies Review (co-ed.
with James Horncastle, open access, published by Simon Fraser UP), War (Hi)Stories (Schöningh), and Genocide and Mass Violence in the Age of Extremes (De Gruyter).
Moreover, Jacob is the curator of the works of Kurt Eisner, whose legacy is published with the support of the Rosa Luxemburg Foundation.
2014: Japanism, Pan-Asianism, Terrorism – A Short History of the Amur Society (Black Dragons) 1901–1945, Academica Press, Palo Alto.
2015: Tabak und Gesellschaft: Vom braunen Gold zum sozialen Stigma, Nomos, Baden-Baden, hrsg.