Despite his own assertions, the work of Emmanuel de Martonne was not limited to a strictly scientific and disinterested domain. His geographical work was necessarily caught up in political circumstances, which is shown clearly in his long and passionate relationship with Romania. In this article we see how this eminent scholar placed himself at the service of the cause of Greater Romania, firstly as a partisan of Romanian intervention in the Great War, then as wartime propagandist, before, at the Versailles Peace Conference, helping draw Romania's post-war frontiers. At the same time, we see how the success of de Martonne's 'scientific' proposals for frontier change was dependent upon military and geopolitical developments. [ABSTRACT FROM AUTHOR]