Born in Ithaca, Metaxas was a career soldier, first seeing action in 1897 fighting the Turkish army in the Thessalian campaign. Following studies in Germany, he returned to join the General Staff and was part of the modernizing process of the Greek Army before the Balkan Wars (1912-1913). He was made Chief of the Greek General Staff in 1913 and was promoted to General.
A staunch monarchist, he supported Constantine I and opposed Greek entry into WW I. Eleftherios Venizelos, the prime minister, resigned over the refusal to aid the Dardanelles campaign and used the war as the major issue in the elections. When Venizelos won the March 1915 elections he mobilised the army but was dismissed by the king. In June 1917, with Allied support and 60,000 Cretan soldiers, the king was deposed and Venizelos empowered, declaring war on June 29, 1917.
After a disputed plebisite George II, son of Constantine I, returned to take the throne in 1935. The elections of 1936 produced a deadlock between Panagis Tsaldaris and Themistoklis Sofoulis. The political situation was further polarized by the gains made by the Communist Party of Greece (KKE). Disliking the Communists and fearing a coup, George II appointed Metaxas, then minister of war, to be interim prime minister.
Widespread industrial unrest in May allowed Metaxas to declare a state of emergency. He suspended the parliament indefinitely and annulled various articles of the constitution. By August 1936 Metaxas was effectively dictator. Patterning his regime on other authoritarian European governments (most notably Mussolini's fascist regime), Metaxas banned political parties, arrested his opponents (around 15,000 Greeks were imprisoned and tortured or exiled for political offences by the Metaxas regime), criminalized strikes and introduced widespread censorship of the media. But he did not have great popular support or a strong ideology.
The Metaxas government sought to pacify the working classes by raising wages, regulating hours and working to improve working conditions. For rural areas agricultural prices were raised and farm debts were taken on by the government. Despite these efforts the Greek people generally moved towards the political left, but without actively opposing Metaxas.
In foreign policy Metaxas was caught in a dilemma. He saw Germany and Italy as 'natural' allies but in the Mediterranean the British and their fleet were a major force while the expansionist goals of Mussolini were clearly threatening to Greece. The uncertain line between the opposing forces was decisively broken by the blunt demands of Mussolini in October 1940. He demanded occupation rights to strategic Greek sites and was met with the single-word reply "no". Italy invaded Greece from Albania on October 28.
The Greeks were able to mount a successful defense, forcing the Italians back into Albania and occupying large parts of Northern Epirus (Southern Albania). Metaxas died in Athens on January 29 of a phlegmon of the pharynx which subsequently led to uncurable toxaemia. He was succeeded by Alexandros Korizis.
Metaxas is a controversial figure in Greek history. He is reviled by some for his dictatorial state, and admired by others for his "No" stance, and his military victory against Italy.