Born in Haguenau into a Jewish family, Eisenmann held a chair at the University of Dijon from 1905.
[1] In 1922 he moved to the Sorbonne in Paris, where he held a professorship and was secretary of the Institute for Slavic Sciences and editor of the Revue historique.
[2] He was also director of the Ernest Denis Institute in Prague and campaigned for the exchange of lecturers and students between Germany and France.
In 1916, Tomáš Garrigue Masaryk and Edvard Beneš founded the Comité national tchèque in Paris, and almost at the same time Eisenmann, Louis Léger, and Ernest Denis founded the Comité national d'études , which also advocated for the independence of a Czech state.
Early in 1918, the French government created a Czechoslovak Legion, which represented a significant auxiliary force at a decisive phase of the war after Russia had made peace.