Hans Gottlieb Leopold Delbrück (German pronunciation: [hans ˈdɛl.bʁʏk] ; 11 November 1848 – 14 July 1929) was a German historian. Delbrück was one of the first modern military historians, basing his method of research on the critical examination of ancient sources, using auxiliary disciplines, like demography and economics, to complete the analysis and the comparison between epochs, to trace the evolution of military institutions. Delbrück's writings are chiefly concerned with the history of the art of war, his most ambitious work being Geschichte der Kriegskunst im Rahmen der politischen Geschichte ("History of Warfare in the Framework of Political History" in four volumes, third edition published in 1920). Other works are Die Perserkriege und die Burgunderkriege (The Persian and Burgundian Wars, 1887), Die Strategie des Perikles erläutert durch die Strategie Friedrichs des Grossen (The Strategy of Pericles Described Through the Strategy of Frederick the Great, 1890) and Das Leben des Feldmarschalls Grafen Neithardt von Gneisenau (Life of Marshal Count Neithardt von Gneisenau, 1894). Source: Wikipedia (en)