Otto was listed on the Nazi Sonderfahndungsliste G.B. ("Special Search List Great Britain"), and was the unofficial head of numerous resistance groups in Central Europe. These groups hated Nazi ideology and saw the resurgence of a Danube confederation as the only way for small states to exist between Germany and Russia. They championed the centuries-old Habsburg principle of "live and let live" among ethnic groups, peoples, minorities, religions, cultures and languages. These imperial resistance groups became embroiled in ferocious partisan warfare against Hitler, who profoundly hated the Habsburg family tradition.Timothy Snyder "The Red Prince: The Secret Lives of a Habsburg Archduke" (2008); James Longo "Hitler and the Habsburgs: The Fuhrer's Vendetta Against the Austrian Royals" (2018); Bob Carruthers "Hitler's Violent Youth: How Trench Warfare and Street Fighting Moulded Hitler" (2015); Pieter M. Judson "The Habsburg Empire. A New History" (Harvard 2016); Christopher Clark "The Sleepwalkers" (New York 2012). Many of these imperial resistance fighters (according to current estimates 4000–4500) were sent directly to concentration camps without trial, and over 800 were executed by the Nazis. Among them was Karl Burian, who was planning to blow up the Gestapo headquarters in Vienna, or Dr. Heinrich Maier, who passed on plans and production facilities for V-2 rockets, Tiger tanks and Messerschmitt airplanes to the Allies. In contrast to many other German resistance groups, the Maier group was informed very early about the mass murder of Jews through its contacts with the Semperit factory near Auschwitz.Elisabeth Boeckl-Klamper, Thomas Mang, Wolfgang Neugebauer: Gestapo-Leitstelle Wien 1938–1945. Vienna 2018, , pp. 299–305.Hans Schafranek: Widerstand und Verrat: Gestapospitzel im antifaschistischen Untergrund. Vienna 2017, , pp. 161–248.Fritz Molden: Die Feuer in der Nacht. Opfer und Sinn des österreichischen Widerstandes 1938–1945. Vienna 1988, p. 122.Peter Broucek "Die österreichische Identität im Widerstand 1938–1945" (2008), p. 163.Hansjakob Stehle "Die Spione aus dem Pfarrhaus (German: The spy from the rectory)" In: Die Zeit, 5 January 1996.
otto was listed on the nazi sonderfahndungsliste gb ("special search list great britain") and was the unofficial head of numerous resistance groups in central europe these groups hated nazi ideology and saw the resurgence of a danube confederation as the only way for small states to exist between germany and russia they championed the centuries-old habsburg principle of "live and let live" among ethnic groups peoples minorities religions cultures and languages these imperial resistance groups became embroiled in ferocious partisan warfare against hitler who profoundly hated the habsburg family traditiontimothy snyder "the red prince the secret lives of a habsburg archduke" (2008); james longo "hitler and the habsburgs the fuhrer's vendetta against the austrian royals" (2018); bob carruthers "hitler's violent youth how trench warfare and street fighting moulded hitler" (2015); pieter m judson "the habsburg empire a new history" (harvard 2016); christopher clark "the sleepwalkers" (new york 2012) many of these imperial resistance fighters (according to current estimates 4000–4500) were sent directly to concentration camps without trial and over 800 were executed by the nazis among them was karl burian who was planning to blow up the gestapo headquarters in vienna or dr heinrich maier who passed on plans and production facilities for v-2 rockets tiger tanks and messerschmitt airplanes to the allies in contrast to many other german resistance groups the maier group was informed very early about the mass murder of jews through its contacts with the semperit factory near auschwitzelisabeth boeckl-klamper thomas mang wolfgang neugebauer gestapo-leitstelle wien 1938–1945 vienna 2018  pp 299–305hans schafranek widerstand und verrat gestapospitzel im antifaschistischen untergrund vienna 2017  pp 161–248fritz molden die feuer in der nacht opfer und sinn des österreichischen widerstandes 1938–1945 vienna 1988 p 122peter broucek "die österreichische identität im widerstand 1938–1945" (2008) p 163hansjakob stehle "die spione aus dem pfarrhaus (german the spy from the rectory)" in die zeit 5 january 1996