This final paper deals with the life and work of Frano Supilo. The paper shows the earliest beginnings of Frano Supilo from his upbringing in his native region, his education, his later political work and his tragic death. Frano Supilo is one of the most important Croatian politicians from the first half of the 20th century. With his work, Frano left a big mark on Croatian politics and stood out as a tireless diplomat in the field of foreign policy. Frano Supilo's political activity was marked by many subterfuges by dissidents, but this did not sway him in his work. Frano had a notable role in drafting the Rijeka resolution and had a prominent position in the Croatian-Serbian coalition. After the outbreak of the First World War, Frano was one of the most active members of the Yugoslav Committee until his resignation from the Committee, which followed various vicissitudes and accusations against Frano. He spent the last years of his life in London, where he died