Leonardas Vilhelmas Grigonis was born on 14 December, 1905 in Rokiškis parish, Pužoniai village. Studied in Rokiškis gymnasium. After graduating, he returned to his homeland. He founded a primary school in Paulianka village. While working as a teacher, he started to Lithuanianize the names of the surrounding villages, he was especially interested in the history of his homeland. Litviniškis village was given the name Sėlynė, where in 1934 a wooden primary school was built by the initiative of L. V. Grigonis. He was also the commander of the Sėlynė village rifle squad, a member of the Rokiškis County Riflemen’s National Committee. After a fire in 1938–1939, which destroyed the wooden school to its foundations, L. V. Grigonis took care of the construction of a new school. 1940 the construction of a new, brick school began on the place of the old school.
1944 L. V. Grigonis left his native land and hid in Žeimiai village (Šiauliai county). In 1948 became a chief of the newly established Resurrection District, later its leader. In the same year in October he moved to a bunker in Minačiai village between Radviliškis and Baisogala. In this bunker in February, 1949 a congress of partisan representatives took place. The Congress announced the establishment of the Lithuanian Freedom Fighting Movement (LFFM). LFFM the Council adopted a Political Declaration, which legitimized itself as a universal organized militant organization against Soviet occupation, and its Council as the only legitimate government in the territory of occupied Lithuania. Jonas Žemaitis-Vytautas was unanimously elected Chairman of the Presidium of the LFFM Council. J. Žemaitis-Vytautas appointed L. V. Grigonis as his third deputy and awarded him 3rd degree Freedom Fighting Crosses (with swords).