He was a member of the Central Committee of the Communist Party of Lithuania in 1927–1958 and chairman of the Supreme Court of the Lithuanian SSR in 1947–1958.

[1] Didžiulis completed just three years of primary education and worked as a farm worker, dockworker and metalworker in Riga before joining the Communist Party of Lithuania in 1919.

The party was illegal in interwar Lithuania and Didžiulis was arrested and imprisoned numerous times, spending a total of about nine years in Lithuanian prisons.

During World War II, he evacuated to Russia and was party representative and organizer in Penza and Pereslavl-Zalessky.

He returned to Vilnius in July 1944 and participated in the Sovietization efforts of Lithuania: land nationalization, mass deportations to Siberia, and suppression of the Lithuanian partisans.

[7] In September 1921, he was tasked by the party with transport and distribution of illegal communist literature, including the periodicals Tiesa and Komunistas [lt].

Even though the Lithuanian police found only legal publications, Didžiulis was confined to a camp in Aukštoji Freda [lt] and later the Fifth Fort of Kaunas Fortress.

[9] After the coup d'état in December 1926, many two members of the Central Committee of the Communist Party of Lithuania were executed while a few others were arrested.

[11] However, he was arrested in January 1928 after the police searched his apartment and found numerous illegal publications.

[14] At the time the Communist Party had two main leaders – Vincas Kapsukas and Zigmas Angarietis – who competed for influence.

[1] According to memoirs of Vincas Krėvė-Mickevičius, Didžiulis was given this assignment (effective July 1) to give communists a majority over Lithuanian nationalist members of the government.

[24] Didžiulis was one of twenty representatives sent to Moscow to request the Soviet Union to accept the newly established Lithuanian SSR as one of its constituent republics.

[27] In July 1944, after Vilnius was retaken by the Soviets as a result of the Operation Bagration, he returned to Vilnius and resumed his pre-war positions: deputy chairman of the presidium of the Supreme Soviet and work in a commission in charge of the land reform.

[29] In October 1951, during the Operation Osen, his sister-in-law Ana and her son were deported from his family's farm in Mandeikiai, but Soviet officials quickly intervened and she was freed from the deportee train in Ostashkov.

On 25 September 1957, the court handed death sentence to Adolfas Ramanauskas, one of the most prominent Lithuanian partisans.