Vasil Petrov Kolarov

When a military coup overthrew Aleksandar Stamboliyski's agrarian government in Bulgaria in June 1923, the Bulgarian Communist Party initially adopted a stance of 'neutrality.' The Comintern harshly condemned the BCP leadership: Stalin went so far as to demand 'a trial of the Communist Party in Bulgaria or its leaders.' As General Secretary of the ECCI, Kolarov returned secretly to Bulgaria to enforce the change of line. Arrested on falsified documents and held for several weeks, he reached Sofia in early August and, together with Comintern functionary Alexander Abramovich, persuaded the Central Committee at its 5–7 August meeting to reverse course and begin rapid preparations for armed action. On 15 September, the Central Committee designated Kolarov, Georgi Dimitrov, Todor Lukanov, and Todor Petrov as the uprising's leadership body; at a 17 September meeting attended only by Kolarov and Dimitrov, 22 September was set as the starting date. The uprising unfolded nationwide but was crushed by government forces. Kolarov and Dimitrov led the remaining fighters across the Yugoslav border into exile. Sentenced to death in absentia, Kolarov would spend the next 22 years in the Soviet Union. The defeat of the September Uprising cemented the political bond between Kolarov and Dimitrov, a partnership that would serve as the backbone of the Bulgarian communist movement until Dimitrov's death in 1949. Though the uprising itself failed, it was subsequently celebrated in communist historiography as 'the world's first anti-fascist armed uprising' and remained central to Kolarov's political identity.

Kolarov served as President of the Executive Committee of the Krestintern (Peasant International) from 1928 until its dissolution in 1939, while also directing the International Agrarian Institute in Moscow, where he guided Marxist research on agrarian questions. The Krestintern was an international peasant organization founded under the Comintern in 1923, aimed at building a united front with radical peasant parties in Eastern Europe and Asia, though it achieved limited success. Kolarov was especially knowledgeable about the smallholder problem in the Balkans; Bulgaria itself being a quintessential small-peasant country, he focused on the revolutionary potential of the rural semi-proletariat and middle peasantry. Under his leadership, the Krestintern published its organ The Peasant International, and the International Agrarian Institute issued scholarly studies on agrarian problems: the Institute outlived the Krestintern itself, continuing until 1942. His theoretical work on the peasant question helped lay the groundwork for Bulgarian communism to appeal not only to urban workers but also to the rural masses, a political asset that proved crucial during the establishment of the People's Republic of Bulgaria after the Second World War.