Nachtigall Battalion
After the invasion of Poland in September 1939, both factions of the OUN collaborated with the Germans and used the opportunity of the invasion to send their activists into Soviet-controlled territory. OUN-B leader Stepan Bandera held meetings with the heads of Germany's intelligence, regarding the formation of Ukrainian staffed forces. On February 25, 1941, the head of Abwehr Wilhelm Franz Canaris sanctioned the creation of the "Ukrainian Legion" under German command. The formation was planned to have 800 persons. OUN-B expected that it would become the core of the future Ukrainian army. In the spring of 1941 the Legion was organized as two units; one unit became known as Nachtigall Battalion, while the other became the Roland Battalion.