only released in the autumn. Through his active participation in war as soldier and scientist Hennig was later subjected to accusations that he had been a member of the National Socialist party, especially by the Italian biologist and founder of panbiogeography, Leon Croizat. No evidence has been officially presented to support the claim. There is no report of Hennig supporting the National Socialist party views publicly on any occasion. Hennig did believe that Nazi Germany would win World War II. During his time as prisoner of war, Hennig began to draft his most important contribution to systematics, not published until 1950. The rough draft was composed with pencil and ballpoint pen into an A4 exercise book, spanning 170 pages. During the war, he also published a further 25 scientific papers. Most of the correspondence and literature research was conducted by his wife, Irma. 1950s: Basic outline of a theory of phylogenetic systematics From 1 December 1945, to 31 March 1947, Willi Hennig stood in for his thesis supervisor Paul Buchner as assistant to Professor Friedrich Hempelmann at the University of Leipzig, giving lectures in general biology, zoology and special zoology of insects. He returned to the German Entomological Institute in Berlin on 1 April 1947, and gave up his position in Leipzig. From 1 November 1949, he led the section for systematic entomology and was second director of the institute. On 1 August 1950, he habilitated in zoology at the Brandenburgische Landeshochschule in Potsdam. On 10 October that year he was offered a professorship with teaching responsibilities, which he fulfilled lecturing on special zoology of invertebrates, systematic zoology and taxonomic practicals. In the same year, he published his Basic outline of a theory of phylogenetic systematics, and further works on the methodology of phylogenetic systematics followed in the ensuing years, accompanied by numerous taxonomic works about Diptera. His two-volume Pocket book of zoology, in which he applied phylogenetic systematics to invertebrates for the first time, was particularly successful. He continued working at the German Entomological Institute in the Soviet Sector of Berlin, Berlin-Friedrichshagen, all the while living in the American sector in Berlin-Steglitz. On a trip to France with his son on 13 August 1961, he heard of the impending Berlin Wall and returned to Berlin immediately to quit his appointment. Moving to East Berlin was out of the question, as Hennig held anti-communist views and already had a troubled