Born in Bijeljina, Bosnia and Herzegovina, Austria-Hungary on 7 June 1900, Čolaković joined the League of Communists of Yugoslavia in April 1919 as a student.

Later, he joined Crvena Pravda ("Red Justice"), a left-wing terrorist organisation which assassinated Yugoslav interior minister Milorad Drašković on 21 July 1921.

[2] While serving his sentence, he made friends with many notable Yugoslav communists, including Moša Pijade with whom he translated Das Kapital and other seminal Marxist texts into Serbo-Croatian.

After his release, Čolaković emigrated to the Soviet Union[2] and in 1937 travelled to Spain to take part in the Spanish Civil War on the Republican side.

[1][3] In addition to writing newspaper articles, propaganda leaflets and books on World War II, he also published two autobiographies Kuća oplakana ("House of Mourning") and Kazivanje o jednom pokolenju ("Stories of One Generation).