As a medical student at the University of Tartu, he joined the Russian Social Democratic Labour Party (bolsheviks) in 1916.

After the collapse of the Soviet regime, Požela joined the underground Communist Party of Lithuania (CPL) becoming a member of its Central Committee in 1921.

[5] The university was closed in February 1918 and Požela returned to his native Bardiškiai where he organized local communist groups (cells).

He played a role in establishing the Samogitian Regiment commanded by Feliksas Baltušis-Žemaitis and organizing a communist revolt in the city on 8 January 1919.

In Raseiniai, Požela published weekly Darbo žodis (Labor's Word) and reestablished Tiesa (Truth) in September 1919.

He published communist Kareivių tiesa (Soldiers' Truth) and legal labor union newspaper Darbininkų gyvenimas (Life of Workers).

The meeting was discovered by the German police and the attendees were arrested leaving Požela who remained in Kaunas essentially the only senior officer of CPL in Lithuania.

[17] In early 1926, Požela together with Zigmas Angarietis prepared and published party position and action plan on the Seimas elections in May 1926.

[19] On 17 December 1926, Lithuanian military organized a coup to overthrow President Kazys Grinius and Prime Minister Mykolas Sleževičius and install Antanas Smetona.

Military's rationale for the coup, which started the 14-year authoritarian regime of Smetona and his Lithuanian Nationalist Union, was that the Bolsheviks were planning a revolt that threatened Lithuania's independence and that a new stronger government was needed to eliminate this threat.

[20] Six communists – Karolis Požela, Juozas Greifenbergeris, Kazys Giedrys, Rapolas Čarnas (Rafail Čiornyj), Faivušas Abramavičius, and Ipolitas Šeluga – were tried by a military court.

The first four received death sentences and were shot by a firing squad on 27 December in the Sixth Fort of the Kaunas Fortress.

[20] Known as the four communards (Lithuanian: keturi komunarai), the four executed communists became the martyrs of CPL with annual commemorative events.

In 1947, their remains were exhumed, cremated, and the burial urns were transferred to a garden of the Vytautas the Great War Museum.

[1] Initially, his brother Vladas Požela [lt] also joined communist and socialist causes, but later became a member of the Social Democratic Party of Lithuania and was briefly Minister of Internal Affairs in the government of Mykolas Sleževičius.

[29] She taught history of the feminist movement at the Communist University of the National Minorities of the West in 1922–24 and worked as a correspondent of TASS in Kaunas in 1924–26.

[32] Their daughter Maja Poželaitė, born in April 1927 in Leningrad, earned a PhD in architecture and worked at the present-day Vilnius Art Academy.