22 September is viewed as the day when the Estonian resistance against the Soviet occupation began in 1944 and as such is observed in Estonia as the Resistance Fighting Day and Otto Tief’s Government Day.
On 22 September 1944 the Soviet Army re-entered Tallinn after the retreat of the German troops. The Soviets ignored the fact that an Estonian constitutional government led by Otto Tief was established four days before, and annexed the country. The Estonian flag on top of the Tall Harmann Tower in Tallinn was replaced with the red communist flag.
Most of the members of the Tief's government were arrested as they tried to evacuate to form a government-in-exile. They were either deported or executed.
The holiday is rejected by Russia, which insists the Soviet troops liberated Tallinn.