- February 5: The Greek government appropriates lignite mines and compensates the proprietors
- May 29: The Battle of Skra commences in World War I.
- May 30: The Battle of Skra, fought in the Macedonia front in World War I, ends in Greek victory over the Bulgarians.
- July 18: Greek-American George Dilboy knocks out three German machine gun nests, continues fighting despite the loss of a leg and finally is killed in the attack on Belleau Woods in World War I. His heroism earned him a posthumous Medal of Honor.
- September 9: The Greek XIV Division, under Maj Gen Ioannis Orfanidis, routs the Bulgarian army at Vremitsa.
- September 15: Greek forces attack the Bulgarians at Monastir.
- September 18: The Battle of Doirani commences in World War I.
- September 19: The Battle of Doirani ends in Allied victory.
- September 21: The Greek I Division liberates Serres.
- September 29: Bulgaria surrenders to the Entente allies in Thessaloniki.
- October 21: The first labor conference in Greece takes place at the Vassiliko Theater of Athens
- October 29: The General Labor Union of Greece (GSEE, Greek:ΓΣΕΕ) is established.
- October 30: Turkey surrenders to the Entente allies in Moudros, Lemnos.
- November 4: The First Congress of Greek socialists is held, from which the Socialist Labour Party of Greece or SEKE (Greek: Σοσιαλιστικό Εργατικό Κόμμα Ελλάδας, Sosialistiko Ergatiko Komma Elladas) was born - a few years later it is renamed to Communist Party of Greece (Kommounistiko Komma Ellados, Κομμουνιστικό Κόμμα Ελλάδος, KKE).
- Date Unknown: Sotiris Versis, athlete