Germany invaded the Soviet Union on 22 June 1941 and Finland declared the Continuation War with the Soviet Union on 25 June 1941. As the Soviet Union retreated, its destruction battalions carried out the scorched-earth tactics. The Erna long-range reconnaissance group was sent from Finland to Northern Estonia on 10 July 1941 to perform reconnaissance of the retreating Red Army, but it eventually engaged the destruction battalions near Kautla forest (Battle of Kautla) on 31 July to 1 August 1941, allowing 2,000 civilians to flee.