After a confrontation with the Quartermaster general of the German army and de facto dictator of Germany, Erich Ludendorff, Groener was reassigned to a field command. However, on Ludendorff's dismissal in October 1918, Groener succeeded him as Erster Generalquartiermeister. Groener then worked with the new Social Democratic president Friedrich Ebert to prevent chaos and a left-wing take-over during the German Revolution of 1918–19. Under his command the military bloodily suppressed leftist uprisings throughout Germany. Yet he also tried to integrate the military, which was dominated by an aristocratic and monarchistic officer corps, into the new republic.
After resigning from the army in the summer of 1919, Groener served in several governments of the Weimar Republic as minister of transportation, interior and defence. He was pushed out of the government in 1932 by Kurt von Schleicher, who was working on a pact with the Nazis. Groener was an obstacle to the pact.
Wilhelm Groener was born in Ludwigsburg in the Kingdom of Württemberg as the son of Karl Eduard Groener (1837-1893), regimental paymaster, and his wife Auguste (née Boleg, 1825-1907) on 22 November 1867. After attending gymnasium at Ulm and Ludwigsburg, where his father had been stationed, Groener entered the 3. Württembergische Infanterie Regiment Nummer 121 of the Württemberg Army in 1884. In 1890, he was promoted to Bataillonsadjutant and from 1893 to 1896 attended the War Academy at Berlin, where he finished top of his class. In 1899, Groener married Helene Geyer (1864–1926) in Schwäbisch Gmünd. They had a daughter, Dorothea Groener-Geyer (b.1900).
As a captain, he won appointment to the General Staff in 1899 and was attached to the railway section, where he worked for the next 17 years. This was only interrupted for the usual assignments to other locations: In 1902 to 1904 he was Kompaniechef of the 98t Infantry Regiment at Metz, in 1908 to 1910 he was with XIII Army Corps, and in 1910 he became a commander of a battalion in the 125th Infantry Regiment at Stuttgart. In 1912, as a lieutenant-colonel, Groener became head of the railway section at the General Staff. His plans for the extension of the railway network and for deployment routes were heavily influenced by the Schlieffen Plan.
The successful deployment of millions of troops and the key role of the railway as a military tool boosted Groener's reputation and he received numerous decorations in 1914. In June 1915, he was promoted to Generalmajor. Due to his organisational skills, in December 1915 Groener was put in charge of food deliveries from Romania. In May 1916, he joined the leadership of the newly created Kriegsernährungsministerium ("War Food Ministry"). In November 1916, as a Generalleutnant he became head of the Kriegsamt and deputy of the Prussian Minister of War.
Together with Erich Ludendorff, Groener there worked on the draft for the Hilfsdienstgesetz (Auxiliary Services Act), which was to lay down rules for the war-time requirement for all men to work (Arbeitszwang). To implement the law, Groener had to negotiate with the civilian bureaucracy, unions and representatives of the employers. Despite his efforts to appear neutral and work with both workers and employers to maximise output, he became the target of criticism. Factory owners resented that he accepted the unions as equal partners. Revolutionary groups used his strict admonishments against those who strike while soldiers die at the front to undermine his standing with the workers. These negotiations made the limits, both physical and social, to Germany's military power obvious to Groener. He thus moved away from the dominant conviction that Germany would win the war. This caused confrontations with the third Oberste Heeresleitung, led by Paul Hindenburg and Ludendorff. During the change at the Reichskanzlei in July 1917, when Georg Michaelis replaced Bethmann-Hollweg as Chancellor, Groener suggested that the state should intervene to limit corporate profits and wage growth that resulted from booming war-related public demand. On 16 August 1917 he was recalled from his post and reassigned to an operational command. This was seen by the public as a response to his views on social policies. First, he served for six months at the western front first as Commander of the 33rd Infantry Division, and then of the XXV Reserve Corps, where he was able to observe trench warfare and the mood of the troops. In March 1918, he commanded the I Army Corps during the occupation of the Ukraine. On 28 March he was appointed chief of staff of the army group Heeresgruppe Eichhorn-Kiew. This task required him to deal with organisational and political challenges, in particular confrontations with the army high command of Austria-Hungary and supervising, then reshuffling, the Ukrainian government which needed help against bolshevik revolutionaries.
After the dismissal of Erich Ludendorff on 26 October 1918, Groener was recalled and on 29 October appointed as Ludendorff's successor as First Quartermaster General (Deputy Chief of the General Staff) under Field Marshal Paul von Hindenburg. Germany′s military situation was becoming untenable under the onslaught of the enemy, and social unrest and rebellion among both the German armed forces and the civilian population threatened to break out into revolution. Groener started to prepare the withdrawal and demobilisation of the army. As the revolution spread through Germany in early November, Groener began to see the Emperor, Wilhelm II, as an impediment to saving the monarchy and the integrity of the army. Privately, he felt the Kaiser should sacrifice himself in a hero's death at the front.
On 6 November, Groener had reacted indignantly to the Social Democrat Friedrich Ebert's suggestion that the Emperor should abdicate. Yet Groener himself advised Wilhelm II on 9 November that he had lost the confidence of the armed forces and recommended abdication to the monarch, when Emperor Wilhelm suggested to use frontline troops to crush the revolution at home. Groener's goal was to preserve the monarchy, but under a different ruler. He was also in favour of accepting the Allies' armistice conditions, despite their severe nature.
On the evening of 10 November, Groener contacted the new chancellor Friedrich Ebert. The two men concluded the so-called Ebert-Groener pact, which was to remain secret for a number of years. For his part of the pact, Ebert agreed to suppress the Bolshevik-led revolution and to maintain the military′s traditional role as one of the pillars of the German state; Groener in turn promised that the still-considerable army would support the new government. For this act, Groener earned the enmity of many other military leaders, many of whom sought the retention of the monarchy.
Over the next weeks, Groener oversaw the retreat and demobilisation of the defeated German army after the signing of the armistice on 11 November 1918. Despite a very tight schedule, the withdrawal was effected without problems. He also had to organise the defence of the eastern borders of the Reich until a peace treaty could be signed. The headquarters of the OHL, at Schloss Wilhelmshöhe from 14 November 1918 to 13 February 1919, were thus moved to Kolberg.
On 23 June 1919, Ebert asked for the OHL's opinion on whether the Reich should sign the Treaty of Versailes. Groener supported signing as he was worried that the unity of the Reich would be in danger if fighting was resumed. He thereby put himself into opposition to the prevailing position of the officer corps and the views of Walther Reinhardt, the Prussian Minister of War. Hindenburg followed Groener on this issue. When Hindenburg resigned his post some days later, Groener became his successor. As the OHL was dissolved with the signing of the treaty, Groener temporarily took over command at Kolberg. He started to organise the establishment of the new peace-time military (Reichswehr), arguing in favour of a high share of former general staff officers among the new leadership including in the Reichswehrministerium. He also supported a senior position for Hans von Seeckt. However, just weeks later, on 30 September, Groener himself resigned from the military. This was against the wishes of Friedrich Ebert, but Groener felt that his pact with the Social Democrat had cost him the trust of many of his fellow officers.
After his resignation from the army, Groener moved in and out of retirement during the 1920s. Not a member of any party, at Ebert's request he served as Transportation Minister between 1920 and 1923. His main achievement was the rebuilding of the Reichsbahn. In 1923, when the Cuno government resigned, Groener left politics and wrote military and political treatises, such as Das Testament des Grafen Schlieffen (1927).
Hindenburg, now Ebert's successor as Reichspräsident, appointed Groener as the successor of Otto Geßler as Defence Minister on 20 January 1928, a post he held until 1932. Besides expanding the Reichswehr, Groener made an effort to integrate it into the society of the Weimar Republic.
In 1930, Groener married Ruth Naeher-Glück (born 1894) in Berlin. They had a son. This second marriage and the early birth date of his son undermined Groener's relationship with the conservative Hindenburg.
On 8 October 1931 he also became acting Interior Minister in the government of Heinrich Brüning, and favoured the banning of the Nazi storm troopers (SA). However, as Interior Minister he was asked to outlaw the SA, whilst his goal as Defence Minister was to integrate it into a national, non-partisan paramilitary force. In April 1932, under pressure from several German states, Groener outlawed the SA and SS. Kurt von Schleicher, his subordinate at the Reichswehrministerium, however wanted to set up a cooperation with these two groups. To that end von Schleicher worked on Hindenburg, trying to have Groener dismissed. He also allied himself with the NSDAP. After a rhetorical defeat in the Reichstag, Groener resigned on 13 May as Defence Minister, urged by von Schleicher who told Groener that he had lost the trust of the Reichswehr. When the government of Brüning fell on 30 May, Groener also lost his position as Innenminister and left politics for good.
He moved to Potsdam-Bornstedt in 1934, where he wrote his memoirs Lebenserinnerungen. Groener died of natural causes in Bornstedt on 3 May 1939. He is buried in the Südwestkirchhof Stahnsdorf, located between Potsdam and Berlin.Pour le Mérite (11 September 1915)
Commander of the Military Order of Max Joseph Bavaria
Officer of the Military Merit Order with Swords (Bavaria)
Knight of the Military Merit Order (Württemberg)
Order of the Red Eagle, 2nd class with Crown and Swords (1917)
Honorary citizen of Ludwigsburg