Beginning in 1932 he served as Minister of War in the cabinet of Franz von Papen, whom he succeeded as Chancellor on 3 December. During his brief term, Schleicher negotiated with Gregor Strasser on a possible secession of the latter from the Nazi Party but their scheme failed. Schleicher then proposed to President Hindenburg to disperse the Reichstag and rule as a de facto dictator, a course of action Hindenburg rejected. On 28 January 1933, facing a political impasse and deteriorating health, Schleicher resigned and recommended the appointment of Adolf Hitler in his stead. Seventeen months afterwards he was murdered on the orders of Hitler during the Night of the Long Knives.
Schleicher was born in Brandenburg an der Havel, the son of a Prussian officer and a shipowner's daughter. He entered the Prussian Army in 1900 as a Leutnant after graduating from a cadet training school. Assigned to the 3rd Foot Guards, he befriended fellow junior officers Oskar von Hindenburg and Kurt von Hammerstein-Equord. In 1909 he attended the Prussian Military Academy, where he met Franz von Papen, and subsequently joined the Railway Department of the Prussian General Staff. Schleicher soon became a protégé of his immediate superior, Wilhelm Groener.
On 28 July 1931, Schleicher married Elisabeth von Schleicher, daughter of the Prussian general Victor von Hennigs. She had previously been married to Schleicher's cousin, Bogislaw von Schleicher, whom she had divorced on 4 May 1931.
After the outbreak of the First World War, Schleicher, now a Captain, was assigned to the General Staff at the Supreme Army Command. During the Battle of Verdun he wrote a manuscript criticising war profiteering in certain industrial sectors, earning him a reputation as a liberal. Aside from a brief period as Chief of Staff of the 237th Division in 1917, Schleicher spent the entire war at Supreme Command. Following the collapse of the German war effort in late 1918, Schleicher's patron Groener was appointed Erster Generalquartiermeister and assumed de facto command of the German Army. As Groener's trusted assistant, Schleicher would become a crucial go-between of the civil and military authorities.
After the November Revolution of 1918, the situation of the military was precarious. In December 1918 Schleicher delivered an ultimatum to Friedrich Ebert on behalf of Paul von Hindenburg demanding that the German provisional government either allow the Army to crush the Spartacus League or the Army would do that task itself.
During the ensuing talks with the German cabinet, Schleicher was able to get permission to allow the Army to return to Berlin. After the November Revolution of 1918, there were demands for the dissolution of the military that had led to such a defeat and the creation of a new military force that would be loyal to democracy, but on 23 December 1918 the Provisional government under Ebert came under attack from the radical left-wing "People's Marine Division". That day a group of Red sailors seemed set to storm and take over the Provisional government when the sailors cut all telephone lines from the chancellor's office to the War Ministry except for a secret one. When Ebert used the secret line to call the War Ministry, it was Schleicher who took the call.
Schleicher played a key role in negotiating the Ebert–Groener pact. In exchange for agreeing to send help to the government, Schleicher was able to secure Ebert's assent to the Army being allowed to maintain its political autonomy. Consequently, the military retained its traditional "state within the state" status with no effective civilian control. When Gustav Noske was appointed Defence Minister on 27 December 1918, both Groener and his protégé Schleicher established excellent working relations with the new minister.