'Winterübung' was the German reoccupation of the demilitarised Rhineland (7 March 1936).

The Allied occupation of the Rhineland in western Germany took place after the Armistice of 11 November 1918 had ended the fighting of World War I. The occupying armies consisted of Belgian, British, French and US forces, and resulted from the implementation of the armistice terms, which demanded the immediate evacuation of German troops from Belgium, France, Luxembourg and Alsace-Lorraine within 15 days.

The US force originally comprised 240,000 men in nine combat-experienced divisions, and was thus nearly one-third of the total occupying force. General John J. Pershing, the US commander-in-chief in Europe, established the US 3^rd Army, under the command of Major General Joseph Dickman, for the purpose. On 24 January 1923 the US Army withdrew from the occupation of the Rhineland.

The Belgian forces comprised five divisions with their headquarters at Aachen and the troops in the Krefeld area.

The British forces entered German territory on 3 December 1918, and the British Army of the Rhine was established as the occupying force in March 1919 with its headquarters at Koblenz.

The French forces were based initially on he 8^th and 10^th Armies. On 21 October 1919 these were combined as the the French Army of the Rhine.

In response to Germany’s 1923 failure to pay reparations as ordained by the Treaty of Versailles in 1919, France and Belgium also occupied Germany’s adjacent industrial area of the Ruhr, leaving it in 1925.

The remilitarisation of the Rhineland by Germany took place on 7 March 1936 as German military forces re-entered the Rhineland. This violated the terms of the Treaty of Versailles and the Locarno Treaties, marking the first time since the end of World War I that German troops had been in this region. Articles 42, 43 and 44 of the Treaty of Versailles, signed in 1919, had ordered that Germany was 'forbidden to maintain or construct any fortification either on the Left bank of the Rhine or on the Right bank to the west of a line drawn 50 km [31 miles] to the East of the Rhine'. If a violation 'in any manner whatsoever' of these articles took place, this 'shall be regarded as committing a hostile act…and as calculated to disturb the peace of the world'. The Locarno Treaties, signed in 1925 by Germany, France, Italy and Britain, stated that the Rhineland should continue its demilitarised status permanently. The Treat of Locarno was regarded as important as it was a voluntary German acceptance of the Rhineland’s demilitarised status as opposed to the dictate of the Treaty of Versailles. Under the Treat of Locarno’s terms, the UK and Italy guaranteed the Franco-German border and the continued demilitarised status of the Rhineland against any 'flagrant violation' without, however, defining what constituted 'flagrant violation'. The Treaty of Versailles also stipulated that the Allied military forces would withdraw from the Rhineland in 1935, although they actually withdrew in 1930. The British delegation at the Hague Conference on German reparations in 1929 proposed that the reparations paid by Germany should be reduced and that the British and French forces should evacuate the Rhineland. Arthur Henderson, the British foreign secretary, persuaded the sceptical Aristide Briand, the French prime minister, to accept that all Allied occupation forces would evacuate the Rhineland by June 1930. The last British soldiers left in late 1929 and the last French soldiers left in June 1930.

Long before the Nazi rise to power in 1933, the German military and diplomatic elites had come to regard the Rhineland’s demilitarised status as only temporary, and planned to remilitarise the Rhineland at the first favourable diplomatic opportunity. Right through the 1920s and early 1930s, the Reichswehr had developed plans for a war to destroy France and its ally Poland, which by their necessity presumed remilitarisation of the Rhineland. In March 1933 General Werner von Blomberg, the war minister, had plans drawn up for remilitarisation. A March 1935 memorandum from Generalleutnant Ludwig Beck, the army chief-of-staff, on the need for Germany to secure Lebensraum (living space), had accepted that remilitarisation should take place as soon as was diplomatically possible. In general, it was believed by the German military, diplomatic and political elites that it would not be possible to remilitarise before 1937.

In his 'peace speech' of 21 May 1935, Adolf Hitler stated that 'In particular, [the Germans] will uphold and fulfil all obligations arising out of the Locarno Treaty, so long as the other parties are on their side ready to stand by that pact.' The sentence was written by the foreign minister, Baron Konstantin von Neurath, who wished to reassure foreign leaders who felt threatened by Germany’s March 1935 denunciation of Pact V of the Treaty of Versailles, which had disarmed Germany. At the same time von Neurath wished to provide an opening for the eventual remilitarisation of the Rhineland, hence the conditional hedging of the promise to obey the terms of the Treaty of Locarno only as long as other powers did so. Late in 1935, von Neurath started rumours that Germany was considering remilitarising the Rhineland in response to the Franco-Soviet pact of May 1935, which von Neurath insisted was a violation of the Treat of Locarno that menaced Germany. At the same time, von Neurath ordered German diplomats to start drawing up legal briefs justifying remilitarisation of the Rhineland under the grounds that the Franco-Soviet pact violated the Treaty of Locarno. In doing this, von Neurath was acting without orders from Hitler, but in the expectation that time was ripe for remilitarisation as a result of the Anglo-Italian crisis caused by the Italo-Abyssinian war.

Early in 1936 Anthony Eden, the British foreign secretary, had secretly unveiled a plan for a 'general settlement' intended to resolve all of Germany’s grievances. Eden’s plan called for a German return to the League of Nations, acceptance of arms limitations, and renunciation of territorial claims in Europe in exchange for remilitarisation of the Rhineland, return of the former German colonies in Africa, and German 'economic priority along the Danube'. As such, the Germans were informed that the British were willing to begin talks on allowing the Rhineland to be remilitarised in exchange for an 'air pact' outlawing bombing and a German promise not to use force to change their borders.

The quid pro quo offer to discuss remilitarisation of the Rhineland in exchange for an 'air pact' placed the British in a weak moral position to oppose a unilateral remilitarisation, since the very offer to consider remilitarisation implied that this was not considered a vital security threat, but something to be traded, which thus led the British to oppose the way that the act of remilitarisation was carried out (namely unilaterally) as opposed to the act itself. In January 1936 during his visit to London to attend the funeral of King George V, von Neurath told Eden that 'If, however, the other signatories or guarantors of the Locarno Pact should conclude bilateral agreements contrary to the spirit of the Locarno Pact, we should be compelled to reconsider our attitude.' Eden’s response to von Neurath’s veiled threat that Germany would remilitarise the Rhineland if the French national assembly ratified the Franco-Soviet pact convinced him that if Germany remilitarised, then the UK would take Germany’s side against France.

During January 1936 Hitler, the German chancellor and Führer, decided to reoccupy the Rhineland. He had originally planned to do this in 1937, but chose early in 1936 to move remilitarisation forward by a year for several reasons including the ratification by the French national assembly of the Franco-Soviet pact of 1935, which allowed him to present his coup both at home and abroad as a defensive move against Franco-Soviet 'encirclement'; the expectation that France would be better armed in 1937; the government in Paris had just fallen and been replaced by a caretaker administration; economic problems at home required the need for a foreign policy success to restore the régime’s popularity; the Italo-Abyssinian War, which had set the UK against Italy and effectively broken up the Stresa Front (formally called the Final Declaration of the Stresa Conference, and as such an agreement between the French prime minister, Pierre Laval, the British prime minister, Ramsay MacDonald, and the Italian prime minister, Benito Mussolini, on 14 April 1935); and apparently because Hitler simply did not feel like waiting an extra year.

On 12 February 1936 Hitler met with von Neurath and his ambassador-at-large, Joachim Ribbentrop, to ask their opinion of the likely foreign reaction to remilitarisation. von Neurath supported remilitarisation but argued that Germany should negotiate more before doing so, while Ribbentrop argued for immediate and unilateral remilitarisation. Ribbentrop told Hitler that if France went to war in response to German remilitarisation, then the UK would go to war with France, an assessment with which von Neurath did not agree but which encouraged Hitler to go ahead with remilitarisation.

On the same day Hitler informed his war minister, Generaloberst Werner von Blomberg, of his intentions and asked the army commander-in-chief, General Werner Freiherr von Fritsch, how long it would take to transport a few infantry battalions and an artillery battery into the Rhineland. von Fritsch answered that it would take three days to organise, but that he was in favour of negotiation as he believed that the German army was in no state for combat with the French army. Beck, the chief of the general staff, warned Hitler that the army would be unable to undertake a successful defence of Germany against a possible retaliatory French attack. Hitler reassured von Fritsch that he would ensure that the German forces would leave at once if the French intervened militarily to halt their advance in what received the codename 'Winterübung'.

At the same time von Neurath started preparing elaborate documents justifying the remilitarisation as a response forced on Germany by the Franco-Soviet pact, and advised Hitler to keep the number of troops sent into the Rhineland very small so to allow the Germans to claim that they had not committed a 'flagrant violation' of the Treaty of Locarno. In the statement to justify the remilitarisation which von Neurath prepared for the foreign press, the German move was portrayed as something forced on a reluctant Germany by ratification of the Franco-Soviet pact, and strongly hinted that Germany would return to the League of Nations if remilitarisation was accepted.

In January 1936 Mussolini, angry about the League of Nations sanctions applied against his country for aggression against Abyssinia, told the German ambassador in Rome, Ulrich von Hassell, that he wanted to see an Austro-German agreement 'which would in practice bring Austria into Germany’s wake, so that she could pursue no other foreign policy than one parallel with Germany. If Austria, as a formally independent state, were thus in practice to become a German satellite, he would have no objection.'

Italo-German relations had been quite bad since mid-1933, and especially since the July Putsch of 1934, so Mussolini’s remarks to von Hassell, indicating that he wished a rapprochement with Germany, were considered significant in Berlin. In another meeting, Mussolini told von Hassell that he regarded the Stresa Front of 1935 as 'dead', and that Italy would do nothing to uphold Locarno should Germany violate it. German officials did not at first believe in Mussolini’s desire for a rapprochement, but after Hitler sent Hans Frank on a secret visit to Rome carrying a message from Hitler about Germany’s support for Italy’s actions in the conquest of Abyssinia, Italo-German relations improved markedly.

On 13 February 1936, in the course of a meeting with Otto Christian Archibald Prinz von Bismarck of the German embassy in London, Ralph Wigram, the head of the Central Department of the Foreign Office, stated that the British government wanted a 'working agreement' for air pact that would outlaw bombing, and that the UK would consider a revision of the Treaties of Versailles and Locarno in Germany’s favour in exchange for an air pact. von Bismarck reported to Berlin that Wigram had hinted quite strongly that the 'things' which the UK was willing to consider revising included remilitarisation.

On 22 February 1936 Mussolini, still angry about the League of Nations sanctions, informed von Hassell that Italy would dishonour the Treat of Locarno if Germany were to remilitarise the Rhineland. Even if Mussolini had wanted to honour the Treaty of Locarno, practical problems would have arisen as the bulk of the Italian army was at that time engaged in the conquest of Abyssinia, and as there was no common Italo-German frontier.

Soon after dawn on 7 March 1936, therefore, 19 German infantry battalions and a handful of aircraft entered the Rhineland and reached the right bank of the Rhine river by 11.00, and three battalions then crossed to the western bank. When German reconnaissance learned that large number of French troops were being concentrated on the Franco-German border, von Blomberg begged Hitler to evacuate the German forces. Hitler inquired whether the French forces had actually crossed the border and, informed that they had not, assured von Blomberg that they would wait until this happened. In marked contrast with von Blomberg, who was highly nervous during 'Winterübung', von Neurath remained calm and urged Hitler to stay the course.

In the event, Germany received nothing but verbal recriminations, though the undertaking did have longer term political and military repercussions.