Greek soldiers fire a cannon over the city of Athens, while the Acropolis can be seen in the background, during celebrations marking the Ohi Day, Greek National Holiday. Ohi Day commemorates the rejection by the Greek Prime Minister Ioannis Metaxas of the ultimatum made by Italian dictator Benito Mussolini on 28 October 1940 and the subsequent Hellenic counterattack against the invading Italian forces.