Ustaše-run puppet state entity Independent State of Croatia (NDH). He operated as an underground collaborator of the KPJ-established People's Liberation Front. While working underground he used the alias name Vladimir Petrović, although due to being a well known and respected lawyer before the war he experienced no trouble with NDH authorities. During March 1942 Velebit left Zagreb and joined the Partisans who mounted a guerrilla resistance to the Nazis and domestic collaborationists. Right away Tito included him in the army's Supreme Command where he mostly worked on establishing some sort of military court authority. Due to his education and knowledge of foreign languages, along with Koča Popović and Milovan Đilas, Velebit was part of the Partisan delegation in Gornji Vakuf and Zagreb at the controversial March 1943 German-Partisan negotiations while the Battle of Neretva raged several hundred kilometers to the south. Velebit and Đilas conducted the negotiations under pseudonyms Vladimir Petrović and Miloš Marković, respectively, while Koča Popović gave his real name. In June 1943, Velebit became the point of contact for foreign military missions in their dealings with the Partisans. Following the death of Ivo Lola Ribar (member of Supreme Command and the chief of Partisan first military mission) on 27 November 1943, Velebit took over his duties. Following the Teheran Conference where the Allies agreed on backing the Partisan resistance exclusively over the Chetnik one, Velebit was sent to the Near East with lieutenant-colonel Miloje Milojević for negotiations over the details and scope of the support. After establishing first contact with the Allies in Cairo, he was on his way to London for further negotiations. Once there, Velebit had meetings with British envoys Fitzroy Maclean and William Deakin over the formal recognition of the People's Liberation Front as a new state entity. In May 1944 Velebit met with Winston Churchill and was also present in Caserta near Naples during Churchill's meeting with Tito on 12 August 1944. Post-war diplomatic career Right after the end of World War II Velebit continued his diplomatic activity. In the Democratic Federal Yugoslavia's provisionary government that got formed on the basis of British-brokered Treaty of Vis and later the Belgrade Agreement, he was the deputy to the Foreign Affairs Minister. He then became one of the chief members of the secret Yugoslav diplomatic mission to Washington, negotiating the terms and scope of the American help to Yugoslavia. After returning home to the country