The Greco-Italian War of 1940-41 to the German Invasion of Greece.
On October 28, 1940, Prime Minister Ioannis Metaxas refused to bow down to Mussolini's demands to hand over the Pindus Mountain range to Fascist Italy. The newspapers in Athens and beyond wrote the headline Oxi (No!)! and Metaxas would go down as a defiant leader in the face of at least on paper a superior military poised to conquer his nation. The Greek people took up their arms and fought against the incursion. The defenders would become the hunters and eventually would secure territory further into Albania, pushing the invader out of their lands.
But success would turn to tragedy, as Mussolini's failures jeopardized Hitler's ambitions of invading the Soviet Union as part of Operation Barbarossa. The German army would invade from Bulgaria and confront the Greek and British and Commonwealth forces. Exhausted both in materials and ammunition, the Greek forces couldn't counter the new invasion force and the country would surrender, but its people would not. Greek resistance after the surrender was fierce and that spirit lives on today as the Greeks don't celebrate the end of the war. They celebrate the spirit of defiance. Oxi.