Yannis Perdikis was born in Pireaus, Greece in 1920. He is a graduate of the Thessaloniki University Law School and of the Political School of the Panteios University in Athens. During the occupation of Greece by the Nazis 1941 1944, he joined the largest underground organization in Athens, the National Democratic Hellenic League (EDES) and soon became a leader of its Young Section. He recruited students and young Greeks in the fight against the occupants. Due to his ardent activities the Germans tried to capture him in the middle of 1943. In September 1943 he was captured by the communists guerillas of ELAS who attempted to establish a communist government in Greece before the liberation. In February 1944 he escaped and returned to Athens. Under the Gestapo threat he continued recruiting members and fighting against the Germans. When the Germans started leaving Athens, in October 1944, he requisitioned the largest hotels in the center of Athens, where he encamped over 1000 members of his organization. He was named Military Commander of EDES for the city of Athens and was commissioned First Lieutenant. The communists attempted to overtake the hotels. A small battle ensued but the communists' attempts were futile. In November 1944 Yannis was ordered by the Commander of the British Forces in Greece, General Scombi, to rejoin the EDES Guerillas Headquarters in Epirus with four of his officers, which were under the control of General Napoleon Zervas. He returned to Athens with the General in February 1945.