Ioannis Trilivas was born in Ithaca on 1 January 1868 (O.S.). He joined the Hellenic Army on 4 May 1885 (O.S.), and after studies at the NCO School was commissioned as an Infantry Second Lieutenant on 4 August 1893 (O.S.). He fought in the Greco-Turkish War of 1897, after which he was transferred for a while to the Hellenic Military Geographical Service, and spent two years in training attached to a French infantry regiment in France. He participated in the Balkan Wars of 1912–13 as a company and battalion commander of the 9th Infantry Regiment, fighting in the battles of Yenidje, Bizani, Kilkis, and Djumaya. By 1918 he was Infantry Chief of the Serres Division, with which he participated in the fighting on the Macedonian front, and especially the Battle of Doiran.