Social and political crises accounted for by differences over the continued participation of Russia in the First World War.

On April 18, 1917, the Foreign Minister of the Provisional Government, the leader of the Kadet Party, Pavel Milyukov, sent a note (an official diplomatic appeal) to the governments of the powers allied in the World War I. The document reaffirmed Russia's loyalty to all treaties and commitments made to the allies by the tsarist government, and its readiness to wage war to the finish. The note contradicted the previous agreements of the Provisional Government and the Petrograd Soviet of Workers' and Soldiers' Deputies, expressed in the Provisional Government's Declaration of War tasks dated March 27, 1917 (waging a defensive war until complete peace was established on the basis of peoples’ self-determination).

On April 20, the publication of the note led to protest rallies in barracks and factories and street demonstrations in Petrograd. More than 25 thousand soldiers gathered, arms in hand, in front of the Mariinsky Palace, the seat of the government, demanding the resignation of Milyukov, Minister of War and Navy Aleksander Guchkov, and then the entire government. By the end of the day, thanks to the efforts of the Petrograd Soviet and the commander of the Petrograd military district Lavr Kornilov, the soldiers were returned to their barracks. The Executive Committee of the Soviet prohibited military units to go out into the streets without its permission in writing.

On April 21, the soldiers remained in the barracks. Although some military units held meetings, they obeyed the decision of the Petrograd Soviet. The Bolsheviks staged workers' demonstrations under the slogan "All Power to the Soviets!", and the Kadet Party in its slogans supported the Provisional Government and Milyukov. Some members of the St. Petersburg Committee of the Russian Social Democratic Labor Party (Bolsheviks), RSDLP(b), used the slogan “Down with the Provisional Government!” Clashes with gunfire and bloodshed took place between the government’s opponents and supporters. Kornilov proposed using the troops to suppress the protests, but failed to obtain the support of the government and resigned.

On the evening of April 21, the Executive Committee of the Petrograd Soviet (except for the Bolsheviks and the Mensheviks-internationalists) approved the explanations of the Milyukov note presented by the government and banned street demonstrations and meetings. On April 22, the Bolshevik Party’s Central Committee adopted Lenin’s resolution on the observance of the resolution of the Petrograd Soviet and condemned the slogans of overthrowing the Provisional Government as untimely.

The April crisis ended with the resignation of Aleksander Guchkov and Pavel Milyukov and the establishment of a coalition government with the participation of socialist ministers (May 5).