Applying to the study of the French Revolution the rules of historical criticism which had produced such rich results in the study of ancient and medieval history, Aulard devoted himself to profound research in the archives and to the publication of numerous important contributions to the political, administrative and moral history of that period. His masterwork was a "Histoire politique de la Revolution française" (4 vol, 3rd ed. 1901). He championed Georges Danton as opposed to Maximilien Robespierre, seeing in Danton the true spirit of the embattled Revolution and the inspiration of the national defense against foreign enemies.