Celebrated throughout Greece on October 28th each year, Oxi day commemorates the answer of the Greek dictator (since August 4th 1936), Ioannis Metaxas, to the Italian ultimatum which asked from Greece to allow Italian forces to use the land of Greece for military operations or otherwise face war. This ultimatum, which was presented to Metaxas by the Italian ambassador in Greece, Grachi, on the dawn (04:00) of October 28th, 1940, after a party in the Italian embassy in Athens, was answered with a single word: oxi! (pronounced 'ochi'; meaning no).

The attack began at 05:30. The days that followed, fierce battles along the mountain range of Pindus broke out, after Italy invaded Greece through Albania. The Greek people responded with decisiveness and rushed to voluntarily enlist in the army. Thanks to the spirit of heroism that characterised the Greek peasants of the mountainous regions of Ipirus (who were carrying military supplies on their backs to the front through mountain paths) and the self sacrifice of the Greek soldiers, the Italian attack was pushed back in a few days. What might have seemed to Mussolini as an easy operation, soon turned out to be a nightmare, when Greece counterattacked and forced the Italian army back deep into Albania (14/11/1940-6/1/1941). The italian attempts to break the Greek lines, until March 1941, were repulsed, with terrible losses from both sides. What makes this Greek victory even more illustrious, is the technical and material superiority of the italian military machine at the time. These events led Winston Churchill to say that the world will no longer say that Greeks fight as heroes, but heroes fight as Greeks.

Hitler had to intervene to save his ally, and by April 1941, a well coordinated attack of the Nazi army had commenced. This move however cost the Nazis, since military forces had to be occupied in Greece instead of the eastern front (Russia) where war was going to break out soon.

Many folk songs have been written about those days and until today, military parades are held each year on this day and school children also parade in their home towns. The balconies of the houses are decorated with Greek flags and it is also a public holiday.