Dimitrios Giatzis was born in Lamia in 1891, and enlisted in the Hellenic Army as a volunteer on 12 March 1910. Promoted to NCO, he took part in the Balkan Wars of 1912–13, and after studies at the NCO School was commissioned as an Infantry Second Lieutenant on 27 December 1914.[2]
He subsequently fought on the Macedonian front during World War I and in the Asia Minor Campaign, first as a company commander and later as a staff officer, being promoted to Lieutenant in 1917 and to Captain in 1920.[2] In the interwar period he served successively as battalion commander, chief of staff of the 3rd Infantry Division, in the staff of II Army Corps, in the Administrative Directorate of the Ministry for Military Affairs, commander of VI Border Sector (1938–40) and briefly chief of staff of the Infantry Inspectorate, before assuming command of III Infantry Brigade in September 1940. During this period he advanced to Major (1923), Lt. Colonel (1931), and Colonel (1935).[2]
Following liberation he joined the re-forming Army, and was named briefly commander of the 2nd National Guard Division in January 1945, before assuming command of the 9th Infantry Division in the next month. On 15 May 1946, he was appointed commander of the newly re-established I Army Corps at Athens, and in February 1947 he became the first commander of the newly formed First Army at Volos. He was moved to the post of Chief of the Hellenic Army General Staff on 1 November, a post he held concurrently with the ad hoc function of Commander-in–chief of the Army following the disbandment of First Army in March 1948, until 20 January 1949, when he retired from service at his own request.[2]
^Note: Greece officially adopted the Gregorian calendar on 16 February 1923 (which became 1 March). All dates prior to that, unless specifically denoted, are Old Style.
^ abcdefg"Αντιστράτηγος ΓΙΑΤΖΗΣ ΔΗΜΗΤΡΙΟΣ του ΧΡΗΣΤΟΥ, ΑΜ 7645". Συνοπτική Ιστορία του Γενικού Επιτελείου Στρατού 1901–2001 [A Concise History of the Hellenic Army General Staff 1901–2001] (in Greek). Athens: Hellenic Army History Directorate. 2001. p. 168. ISBN960-7897-44-7.
§ Substitute Chiefs of the General Staff for the Rear Areas/Interior (as opposed to the Field Staff) † Deputy Chiefs substituting during vacancies ‡ Under the title "Chief of the Army"