This article deals with the genesis of the Bilderatlas Mnemosyne, composed by Aby Warburg between 1927 and 1929 as a response to the Great War. His reaction to the war was both pathetic (even pathological) and epistemic (which is to say, methodological). If the history of culture amounted to a great psychomachia of the astra (concepts) and the monstra (chaos), as Warburg said, the war was for him a direct test of his theory (or Kulturwissenschaft). It should be no surprise, then, that between 1914 and 1918 he should assemble a large iconographic collection of materials from and about the war. This essay compares that collection and its theoretical foundations with similar projects of Warburg's contemporaries in France and Germany (notably those of the historians Lucien Febvre and Marc Bloch).