today we are writing with the sad news that our colleague Uli Eumann has passed away last week.
One of the founders of the HNR community, Uli had initially subscribed to the 2008 Trier Summer School on Social Network Analysis, where the rest of us met. In advance of the summer school, he found that had already taught himself everything he needed to know from SNA to be able to conduct his research on historical networks, so he canceled his participation. Still, on the list of the Summer School participants, most of them social scientists, he stood out as yet another contemporary historian. When the rest of us decided that we wanted to start our own initiative to determine what it means to do historical network analysis, we luckily also reached out to Uli. His research on the networks of communist resistance in Cologne in the 1930s perfectly lined up with our own.
Uli was one of the the driving forces behind HNR in its very early days. He proposed and hosted the first HNR workshop in Cologne to which he invited visualization expert Lothar Krempel with whom he had also collaborated early on. During the time of our active collaboration, Uli’s research focused on National Socialism and working class resistance but also on the history of worker movements, modern slavery, the Spanish Civil War, Communism and the social history of the German Communist party during the Weimar Republic (the latter being his PhD project which he had defended at Cologne University in 2004).
In his historical network-related research, Uli used network analysis and visualizations as a means to think through complex historical relationships. One illustration of his genuinely original approach is a network graph based on Gestapo interrogation reports. Uli mapped the interplay between the evolving knowledge horizons of both the Gestapo and captured activists based on the names of co-conspirators the latter gave away under interrogation. On this basis, he successfully reconstructed up to which point prisoners only shared information they anticipated was already known by the Gestapo but also the points when individuals broke down and shared all they knew. He visualized the evolution of these knowledge horizons in form of a static representation of the network dynamics, which to this day can serve as a best practice example for the effective, argument-driven communication using graph structures.
We concluded our joint work on historical networks with the organization of the first international HNR conference in Hamburg and the publication of the Handbuch Historische Netzwerkforschung, which he co-edited and to which he contributed a chapter on historical heuristics and hypotheses testing.
Besides his academic interests, Uli was a keen photographer and frequently visited Barcelona, a city which held a special place in his heart. We will remember Uli as a sharp, critical and quick-witted colleague but also as a warm person with a big heart and great sense of humor.
Marten Düring, Linda von Keyserlingk-Rehbein and Martin Stark