Born as Jānis Daumanis in a peasant family on March 18, 1884, at hamlet Bikern near Riga, in 1901 he graduated the Baltic Teacher Seminary becoming a people's teacher. The same year in 1901 Gaven joined the Social Democratic Labour Party and until 1905 worked as a secretary of Riga's party organization. During the 1905 Revolution, he was a leader of militant formations of peasants in Livland Governorate and in 1906 he became a member of the Central Committee of the Social Democracy of Livland Krai. On February 6, 1908 Gaven was arrested and until the start of World War I he spent time in katorga centers of Riga and Vologda, after which Gaven was exiled to Minusinsk. After the February Revolution on March 3, 1917, Gaven was released and became a chairman of the local Minusinsk Communa at the same time he also was one of the organizers of the Congress of Soviets of the Middle Siberia. In September 1917 Gaven was delegated to the All-Russian Democratic Conference in Petrograd, after which at the end of September with Bolshevik mandate he was sent to Sevastopol. For some 11 days Gaven spent in Simferopol awaiting to be allowed in Sevastopol. On November 6–10, 1917 Gaven was heading the so-called "First Black Sea Fleet Congress" in Sevastopol, which adopted Bolshevik resolution on power and sanctioned to send ships and sailors in fight against Alexey Kaledin. On November 20, 1917 Gaven was a delegate of the Governorate Congress of Soviets in Simferopol and the Bolshevik regional conference on November 23–24, 1917. At night on December 15–16, 1917 he was one of the leaders of an uprising of sailors which resulted in establishing of the Soviet regime in Sevastopol by creating the Sevastopol military revkom. Gaven was in charge of the arrests, tortures and mass shootings that accompanied the uprising. From December 18, Gaven headed the Presidium of Soviet of soldiers and workers deputies, the city's Bolshevik committee and was a chief editor of the newspaper "Tavricheskaya Pravda". He retired in 1933. During the Stalinist purges Gaven was arrested in 1936 and accused of “counterrevolutionary” activities. Gaven was set to be trailed, but being too sick to appear at his trail he was taken from his sickbed outside on a stretcher and shot dead on 4 October 1936.
