J.Jakavonis was involved in armed resistance from the age of 19. In 1945, he and other partisans set up a bunker in the courtyard of his parents' house, which was the headquarters of the Southern Lithuanian partisan commanders in 1945-1946. The bunker was the home and workplace of the commanders Juozas Vitkus-Kazimieraitis and Adolfas Ramanauskas-Vanagas, and the partisan newspaper "The Liberty Bell" was published. Jakavonis was also a distributor of the underground press. After two years of active partisan struggle, on 8 December 1946, he was arrested by the Enkavedists with the partisan press in his home village, at the home of a neighbour. He was then interrogated and tortured in the cellars of the Merkinė militia, in Varėna, and finally in the cellars of the Vilnius KGB. Having endured terrible torture, Jakavonis did not betray a single comrade. He was convicted by the Bolshevik authorities - from 1946 he was sent to Kolyma [Siberian] prisons. He returned to Lithuania with his family in 1959.
In 1988, with the beginning of the Revival, Jakavonis joined the activities of the Sąjūdis. A bunker was unearthed near his home and installed as a former Southern Lithuanian partisan headquarters.
