The beginning of the Soviet aggression on Poland. Soviet troops meet the resistance of the Border Guard Corps (KOP), including "Sarny" Regiment, "Małyńsk" Grouping, "Kleck", "Ludwik", "Sienkiewicze", "Dawigródek" battalions, and Polish Army units (often formed ad hoc, e.g. Reserve Cavalry Brigade Wołkowysk) in many points along the border and deep within the Polish territory, including near Kowel, Sarny, Baranowicze, Dubno, Orany and Tarnopol. In the organization of Polish defense a special role is played by the Deputy Commander of the Border Guard, General Wilhelm Orlik-Rückemann.
In the evening, the President of the Republic of Poland, Ignacy Mościcki, and the government of the Republic of Poland cross the border with Romania.
The beginning of the Soviet murders of Polish officers and intelligentsia, in which, hand in hand the units of the Soviet army and the NKVD, representatives of national minorities collaborating with the Soviet occupant take part.