[1][2] Vincas Mickevičius was early exposed to old illegal issues of Auszra monthly magazine hidden at their home.

After graduating from the Gymnasium in 1897, Mickevičius enrolled at the Sejny Priest Seminary, but was expelled after a year for his illegal political activities.

[4] He at that time belonged to the federalist wing of the LSDP, which promoted the idea of an independent Lithuania in a federation with Poland, Belarus, Ukraine and Latvia (former territories of the Polish–Lithuanian Commonwealth).

During the Revolution of 1905, Mickevičius organized anti-tsarist peasant demonstrations and strikes in Suvalkija and northern Lithuania.

In December 1905, he was arrested under the name of J. Jaks-Tyris and convicted of revolutionary activities, but managed to escape from a prison hospital in Suwałki in 1906.

Among his defenders in the Suwałki court were attorneys Alexander Kerensky, who, after the 1917 February revolution, was the head of Russian government, and M. F. Volkenstein, who employed V. Ulyanov (Lenin) back in 1893.

[4] In 1909, after authorities discovered that Mickevičius was the same person who escaped from prison in 1906, he was sentenced to an additional 8 years of katorga.

In 1913, to commemorate the 300th anniversary of the Romanov Dynasty, Tsar Nicholas II decreed the amnesty for certain non-violent prisoners.

With the help of local activists, Mickevičius crossed the border to Prussia and traveled to Austria with fake documents.

In 1914 in Kraków, then part of the Austrian Grand Duchy of Cracow, he met Vladimir Lenin, the leader of the Bolshevik faction of the Russian Social Democratic Labour Party.

[6] He edited left wing science and literature monthly magazine Naujoji Gadynė in Philadelphia and newspaper Kova.

He arrived from the United States to Petrograd and joined the Russian Social Democratic Labor Party (Bolshevik) (RSDLP(b)).

In August 1917, he participated in the 6th congress of RSDLP(b) in Petrograd and supported the creation of the Communist International (Comintern).

[7] On 8 December, the Vilnius Soviet formed the Provisional Revolutionary Workers' and Peasants' Government of Lithuania.

On 16 December, the Mickevičius government issued a manifesto, in which they dismissed German occupational administration and proclaimed the Lithuanian Soviet Socialist Republic.

[5][8] German occupying forces were still stationed in Vilnius but started leaving in late December 1918, while the Red Army attacked westward trying to seize as many of the lands lost by the Treaty of Brest-Litovsk.

[8] From 1921 until 1935, Mickevičius was on the editorial board of Lithuanian communist periodicals Tiesa, Kibirkstis, Balsas, Komunaras, and Komunistas.

His wife, Elena Domicėlė Tautkaitė, was executed in 1937 for "Trotskyist activities" and their three children were adopted and taken home by their maternal aunt.

Their Lithuanian origin and relatively weak Polonization were responsible for the nationalist character of this movement, while their peasant roots shaped the social program.

Vincas Kudirka was a member of the Proletariat Party and was arrested when he was helping re-print Marx's Das Kapital, and Mickevičius called himself a social-patriot.

[4] According to writer Ona Pleirytė-Puidienė [lt], a witness of the 1905 revolution,[10] Kapsukas was literally the social democratic party's and Lithuanian idea's martyr.

Always breathless, hungry, without real shelter he travelled across Lithuania spreading national awareness and enlightenment.

During his prison years (1907–1914), Mickevičius read works of Marx, Kautsky, Plekhanov and other Marxists and his views drifted profoundly toward Marxism.

Later in exile and emigration, he met Yakov Sverdlov, Vladimir Lenin, Nikolai Bukharin and Leon Trotsky who also influenced his views.

However, until his last days Mickevičius venerated his mentor Vincas Kudirka and retained deep respect for Povilas Višinskis.

[citation needed] Between 1937 and 1953, Mickevičius was on Stalin's "gray list," not officially an "enemy of state," but not to be mentioned in public.