In February 1920, the 1st Congress of the Communist Party of Azerbaijan legally took place in Baku and made a decision about preparation of the armed revolt. On 27 April of the same year, units of the Russian 11th Red Army crossed the border of Azerbaijan and began to march towards Baku. Soviet Russia presented the Azerbaijan Democratic Republic with an ultimatum to surrender, and the troops entered Baku the next day, accompanied by Grigory Ordzhonikidze and Sergey Kirov of the Bolshevik Kavbiuro. The city became a capital of the Azerbaijan SSR and underwent many major changes. As a result, Baku played a great role in many branches of the Soviet life. Since about 1921, the city was headed by the Baku City Executive Committee, commonly known in Russian as "Bakgorispolkom". Together with the Baku Party Committee (known as the "Baksovet"), it developed the economic significance of the Caspian metropolis. From 1922 to 1930, Baku was the venue for one of the major Trade fairs of the Soviet Union, serving as a commercial bridgehead to Iran and the Middle East.