The Declaration of Ukrainian Independence of June 30, 1941 was announced by the Organization of Ukrainian Nationalists (OUN) under the leadership of Stepan Bandera, who declared an independent Ukrainian State in Lviv. The prime-minister was Yaroslav Stetsko, and the head of Council of Seniors was Kost Levitsky.
The OUN intended to take advantage of the retreat of Soviet forces from Ukraine. Some members thought that they had found a new powerful ally in Nazi Germany to aid them in their struggle against the Soviet Union. Days after the Nazi invasion of Lviv, however, the leadership of the newly formed government was arrested and sent to concentration camps in Germany. Within two years of the declaration, the Nazis had imprisoned or killed 80% of OUN-B leadership.
After World War I, Ukraine was divided into three parts: most of Central and Eastern Ukraine became the Ukrainian Soviet Socialist Republic in 1921. The capital was Kharkiv.
The majority of current Western Ukraine became part of the Second Polish Republic. This included the city of Lviv, which at the time was the center of Ukrainian nationalist activity.
A small part of current far Western Ukraine, the Zakarpattia, became part of Czechoslovakia.
For various reasons, the Ukrainian nationalist movement was more active in Western Ukraine than in Central Ukraine in the inter-war period. At the end of World War I, veterans of the Sich Riflemen created the Ukrainian Military Organization in 1920 to promote the creation of an independent Ukrainian state. The leader was Yevhen Konovalets.