September Conspiracy

The September Conspiracy was an attempt by German opponents of Adolf Hitler to stop the threatened invasion of Czechoslovakia and, if the opportunity arose, remove Hitler from power. It was not a settled military uprising: its leaders depended on the Army’s conditional willingness to intervene, a small force prepared to arrest Hitler, and a crisis that might unfold within hours. The postponement of mobilisation exposed how much the plan rested on timing and on decisions made by others; with the Army still hesitant, the conspirators shifted their effort toward preventing an agreement at Munich.

Crisis and political stakes

The plot took shape amid the prospect that Germany would invade on Saturday. Neville Chamberlain told the British Chiefs of Staff that Hitler had rejected even a short wait for the orderly transfer of the Sudeten territory, despite the proposed plebiscite and the Czechoslovak Government’s agreement. Sir Horace Wilson had warned Hitler that if France fulfilled its treaty obligations to Czechoslovakia, Britain would be obliged to support France. Hitler’s reported response was that he was prepared for every eventuality and expected war by the following Monday. The danger was not merely a distant possibility: decisions about mobilisation, alliance commitments, and whether Hitler was bluffing had become urgent.

The British Cabinet also considered partial mobilisation. Chamberlain recognized that it would mean mobilising before Germany and worried that a visible challenge might drive Hitler into war rather than deter him. The argument for the measure was that it could demonstrate Britain’s readiness to fight and prevent Hitler from mistaking peace efforts for weakness. This debate framed the conspirators’ own dilemma: a firmer response might help bring about the Army’s intervention, but the threat of war was also the very danger the plot aimed to prevent.

The Army’s conditional opening

At a meeting with Colonel Hans Oster, Hans Bernd Gisevius, and others, General Ludwig Beck disclosed the limits and possible importance of his position. He had resigned as Chief of the General Staff nearly six weeks earlier in protest at the plan for war with Czechoslovakia, but had promised Hitler to keep his resignation private. Beck regretted giving his word; nevertheless, he remained in contact with former colleagues in the high command. He reported strong opposition there and judged that if Hitler ordered mobilisation the next day, the Army might disobey and move against the regime.

That possibility was constrained by the Army’s oath of loyalty to Hitler. Beck explained that the Army could enter the Chancellery to maintain order if a disturbance occurred, but could not make the first move against Hitler itself. Oster and Captain Friedrich Heinz had worked out a way to exploit that distinction: surprise, an initial force of about fifty experienced fighters, and an assurance that the Army would prevent the SS from mounting a rescue attempt could make an arrest possible. Heinz said the men were already available and prepared to move the next day. The plan therefore required both a small civilian-led action and a much larger institution willing to intervene afterward.

The conspirators agreed that the immediate objective was to stop Hitler issuing the mobilisation order the following afternoon, rather than decide in advance what government should replace the Third Reich. Oster’s proposed terms made the danger of failure explicit: if Hitler surrendered, they would take him alive; if he seemed likely to escape, they would shoot him. Paul von Hartmann was the first to agree, and the others followed, with Beck’s assent coming last and reluctantly. They ended the meeting resolved to strike the next day if circumstances demanded it.

The postponement and the failed military expectation

The turning point came when Sir Nevile Henderson telephoned Neville Chamberlain’s office with news from Berlin. Benito Mussolini had sent Hitler a message promising Italy’s support in the event of conflict while asking him to postpone mobilisation for twenty-four hours so the situation could be reconsidered. Hitler agreed. The pause postponed the immediate decision on which the conspirators had built their opportunity; it did not amount to cancelling mobilisation or abandoning the threat of invasion.

At five o’clock that afternoon, the core group met in Erich Kordt’s office in the Prussian State building. It consisted of Gisevius and Count von Schulenburg from the Interior Ministry, Hans von Dohnányi from Justice, Oster from the Abwehr, and Kordt and Hartmann from the Foreign Service. Their cover story was that they had met informally to discuss an inter-departmental planning group for the newly liberated Sudeten territories. The ordinary bureaucratic setting and the innocuous explanation offered concealment, but the small size of the group also sharpened Hartmann’s doubt: six men were trying to bring down a dictatorship controlling a country of eighty million.

Oster explained that the Army’s decision had ultimately depended on Walther von Brauchitsch. When Hitler postponed mobilisation, Brauchitsch was still deciding what to do. The conspirators therefore had no assurance that the Army would have acted even if the order had gone ahead. Oster cited indications that Franz Halder was sympathetic, but Hartmann challenged the reliance on second-hand reports and argued that a genuinely committed Army leadership would already have acted. The dispute revealed the difference between opposition in principle and a willingness to risk a coup at the decisive moment.

Limits of military resistance and the next objective

Oster clarified that the Army’s opposition was conditional: it would act only if convinced that Germany was heading into war with Britain and France. When Hartmann asked whether this meant the officers expected Germany to lose, Oster agreed. The Army’s resistance, as described in the meeting, was not a moral rejection of Hitler’s regime. Its leaders judged the danger through Germany’s military prospects. Hartmann drew the consequence sharply: while Hitler appeared to be winning, the Army would leave him safe; by the time it turned against him, it might be too late. Kordt warned him to lower his voice because Rudolf Hess’s office was nearby.

Oster said he had spent months trying to prepare the Army and had sent messages to London throughout the summer, urging the British to stand firm so the German conspirators could act. He blamed British and French timidity for undermining that prospect. Hartmann, however, focused on what remained possible after Hitler’s acceptance of the delay. If the conspirators could not act without the Army, they might still try to prevent the agreement expected to be signed the next day at Munich. Kordt considered the conference effectively a formality, since Hitler seemed likely to receive what Britain and France had already offered. Hartmann answered that mobilisation had been postponed, not cancelled.

The conspiracy thus changed from a planned arrest operation tied to an imminent mobilisation order into an attempt to obstruct the diplomatic settlement. The evidence establishes neither that the Army would certainly have moved nor that the conspirators had a reliable route to success. It shows instead a precarious chain of dependencies: Beck’s concealed resignation and contacts, the Army’s oath and military calculations, the readiness of roughly fifty men, and the timing of Hitler’s order. Mussolini’s intervention broke that chain at its most immediate point. With the coup opportunity deferred and the Munich agreement approaching, Hartmann and his colleagues redirected their resistance toward the conference itself.