Hans Paul Oster (9 August 1887 – 9 April 1945) was a German general in the Wehrmacht and a leading figure in the military resistance to Adolf Hitler. As deputy head of the counter‑espionage bureau in the Abwehr, he used his position to support and coordinate opposition activities under the cover of intelligence work.
Oster played a central role in the Oster conspiracy of September 1938 and helped reorganize the resistance network at the outbreak of the Second World War. During the Phoney War, he warned the Dutch government of Germany’s impending invasion, and he later worked closely with figures such as Ludwig Beck, Helmuth Groscurth, and Hans von Dohnanyi. Arrested in 1943 after the exposure of anti‑Nazi activities within the Abwehr, he was implicated again when the secret diaries of Admiral Wilhelm Canaris were discovered in April 1945. Oster was executed at Flossenbürg concentration camp on 9 April 1945.
Oster was born in Dresden, Saxony in 1887, the son of an Alsatian pastor of the French Protestant Church. He was raised in the environment of the Wilhelmine Empire and was an enthusiastic admirer of the monarchy throughout his life, while at the same time, he was distinguished by his liberal, tolerant attitude and appreciation of Christian-humanist traditions, as well as his enjoyment of French language and culture.
In 1907, Oster entered the artillery corps and during World War I served on the Western Front until 1916, when he was appointed as captain to the German General Staff. After the war, he remained in the reduced Reichswehr, whose officer corps was limited to 4,000 by the Treaty of Versailles. He had to resign from the army in 1932 as punishment for his affair with a married woman.
He soon found a job in a new organisation that Hermann Göring established under the Prussian police, before transferring to the Abwehr in October 1933—where he met Hans Bernd Gisevius and Arthur Nebe, then working in the Gestapo, and became a confidant and deputy to Admiral Canaris.
Not long after Hitler and the Nazis came to power, Oster had already taken a critical attitude toward the regime and its leadership. Then, during the summer of 1934, in the wake of the events surrounding the Röhm affair, Oster's former superior Kurt von Schleicher was murdered; an event that turned Oster into a "fierce opponent" of the Nazis. German historian Walter Goerlitz characterized Oster not merely as an anti-Hitlerite like his co-conspirators, but wrote that he (Oster) was "especially determined" to maintain contact with "Hitler's underground enemies."
In 1935, Oster was allowed to re-join the army but not as a member of the General Staff. By 1938, the Blomberg–Fritsch Affair and Kristallnacht (the Nazi-led pogrom against Jews in Germany), turned his antipathy into a hatred of Nazism and a willingness to help save Jews. During the Fritsch crisis, Oster met Generaloberst (Colonel General) Ludwig Beck, Chief of the General Staff, for the first time, making the connections for the Oster conspiracy of September 1938. Hans Rothfels, one of the early historians writing on the German resistance networks, described Oster as "a clear-cut figure" who was "not merely the 'technician' who covered up the conspiracy and maintained…valuable contacts" but "one of the main driving forces" of the resistance itself. German historian Hans Mommsen claims similarly, identifying Oster as "perhaps the most striking example of an officer who, from 1938 onwards, systematically resisted the regime," and as one who "uncompromisingly confronted" the dilemma Bonhoeffer articulated regarding Christian civilization's chances for survival in the face of Nazi tyranny and criminality.
Oster's position in the Abwehr was invaluable to the conspirators, since the organisation could provide false papers and restricted materials, disguise conspiratorial activities as intelligence work, link disparate resistance cells, and supply intelligence. The first military-backed conspiracy to overthrow Hitler resulted from the Fuehrer's intention to invade Czechoslovakia, which Oster and others in his circle opposed. In August 1938, Beck spoke openly at a meeting of army generals in Berlin about his opposition to a war with the Western powers over Hitler's plan against Czechoslovakia. When Hitler was informed of Beck's misgivings, he demanded and received Beck's resignation. Beck was highly respected in the army and his removal shocked the officer corps. His successor as Chief of Staff, Franz Halder, remained in touch with him and also with Oster. Privately, he said that he considered Hitler "the incarnation of evil".
Oster, Gisevius and Hjalmar Schacht urged Halder and Beck to stage a coup against Hitler. Not only did Oster want to remove Hitler from power, he also was convinced that the resistance needed to eliminate SS-Reichsführer Heinrich Himmler and the Gestapo. However, the army generals argued that they could mobilise support among the officer corps only if Hitler made overt moves towards war. On Oster's recommendation, Halder conferred with Schacht about plans for a coup by 15 September, and it was eventually agreed that Halder would instigate the coup when Hitler committed an overt step towards war.
A replacement government had already been envisioned by the resistance planners. Correspondingly, the constitutional blueprint worked out in the summer of 1938 by Oster, Fritz-Dietlof von der Schulenburg, and Friedrich Heinz—central to Oster's vision of a post-Nazi refashioning of Germany—fused a völkisch-nationalist agenda with Prusso-German socialism under a restored "German monarchy," a synthesis owing no small debt to Friedrich Naumann's concept of a "democratic imperium (Kaisertum)."
Emissaries from among the conspirators traveled to Britain, with the assistance of Oster and the Abwehr, to urge the British to stand firm against Hitler over the Sudeten crisis. Oster urged Erich Kordt, head of the Ministeramt, to extract from London an unequivocal threat of British intervention, convinced that only a blunt warning might restrain Hitler. He helped channel a steady stream of intelligence to London and Paris indicating that an attack on Czechoslovakia was imminent. Yet despite these efforts—and despite intermediaries such as Ewald von Kleist stressing the personal risk involved—the British response remained noncommittal, leaving Oster's initiative without effect.
To some degree, Oster had exaggerated matters to elicit fear and support, which was significantly allayed by the subsequent negotiations between Germany and Britain. On 28 September, the British Prime Minister Neville Chamberlain agreed to a meeting in Munich, where he accepted the dismemberment of Czechoslovakia. Hitler's diplomatic triumph undermined and demoralised the conspirators. Until that time Halder seemed keen to stage a coup.
Outbreak of war and reorganization of the resistance (1939)
In the autumn of 1939, many of the senior military and Foreign Office figures who had moved toward opposition during the Sudeten crisis concluded that Hitler’s removal was the only means of effecting real change within the regime. Oster, with Canaris's support, worked to make the Abwehr the center of a renewed oppositional network, building on contacts established the previous year. He placed his trusted associate Helmuth Groscurth as liaison to Halder at the Army High Command in Zossen and encouraged the appointment of other opponents of the regime—such as Hasso von Etzdorf—to key liaison posts.
Oster also brought Hans Dohnanyi onto his staff to expand these contacts and maintain links with former Army Chief Ludwig Beck; many regarded him as the figurehead of the emerging resistance. Despite growing alarm over Hitler's determination to press ahead with an attack on France and Britain, members within the network remained fragmented and hesitant. By the end of 1939, no attempt to remove Hitler had materialized, and the weaknesses of the nascent resistance were already evident.
As war again grew more likely in mid-1939, the efforts for a coup were revived. Oster was still in contact with Halder and Witzleben. In August, along with Gisevius, Schacht and Thomas, he decided to do something what Gisevius described as "one last desperate step." Schacht, Gisevius, Thomas and Canaris proposed to go to Zossen, thinking that since Schacht was still Reichsminister, he would not be denied access. Later, on 25 August, at the Abwehr office on the Tirpitzufer, they proposed to confront Halder and Brauchitsch with an ultimatum: since the decision for war had not been discussed by the Reichskabinett, it was unconstitutional, and the Army must either place troops at Schacht's disposal to uphold the Reich government or arrest those present who supported Hitler. The latter option was discouraged by the threat that the conspirators would expose their earlier agreements.