An attempt by the Supreme Commander-in-Chief of the Russian Army, General Lavr Kornilov to establish a military dictatorship and reorganize the government (end of August 1917).

After the failure of the June offensive on the front, the Head of the Provisional Government, Alexander Kerensky discussed measures to strengthen discipline in the army with the representatives of the army command. On July 12, the government approved the introduction of the death penalty at the front on the initiative of the commander of the Southwestern Front armies, General Lavr Kornilov. However, Kornilov’s proposal to introduce revolutionary military courts throughout the country and use the death penalty in the rear was deemed excessive. Nevertheless, on July 18 Kornilov was appointed Supreme Commander-in-Chief and continued to actively advocate the strengthening of discipline in the army and the establishment of “solid power” in the country.

Kerensky and Kornilov discussed “restoring order” in Petrograd. Kerensky tentatively approved the arrival of Aleksander Krymov’s 3rd Cavalry Corps in Petrograd to this end. On August 25, Kornilov ordered the troops to move to Petrograd. He planned to establish military control over the capital, disperse the Soviets, apply repression against the left forces, and reorganize the government. On the one hand, Kerensky was interested in obtaining Kornilov's support to fight radical forces (Bolsheviks). On the other hand, he did not share the plans of the military concerning the Soviets and committees regarding them as a threat to his power. Kerensky assumed that General Kornilov was striving to concentrate power in his own hands, and sent him a telegram instructing him to surrender his post and come to Petrograd. Kornilov did not obey the order and continued his march.

Soon, Kerensky ordered to return the troops to their previous dislocation and declared Kornilov’s dismissing from office and bringing him to trial over mutiny. Kornilov stated that the Provisional Government fell under the influence of the Germans and the Bolsheviks and called for the establishment of a government of national defense. Kerensky gained the support of the Central Executive Committee of the Soviets of Workers' and Soldiers' Deputies, which initiated the establishment of the Committee for the People's Struggle against Counter-Revolution. Petrograd workers began to arm themselves, and Red Guard detachments were formed. Kornilov’s troops were stopped near Petrograd and changed their views as a result of awareness-raising (propagandist) conversations.

On August 30, Alexander Kerensky took over the functions of the Supreme Commander-in-Chief. However, he suffered significant reputational damage due to his ambiguous position during the Kornilov affair. Lavr Kornilov and his supporters were arrested and sent to the Bykhov prison (the town of Bykhov, Mogilyov governorate). Later they became founders of the White movement. The developments of the end of August 1917 undermined the authority of the Provisional Government and strengthened the position of the left-wing parties and groups, especially Bolsheviks.