Ohi Day, celebrated on October 28th, commemorates Greece's refusal to surrender to Axis forces during World War II in 1940. The day marks the response of Greek Prime Minister Ioannis Metaxas to an ultimatum from Mussolini, which led to Greece entering the war. This act of defiance is seen as a symbol of national pride and resistance. The celebration includes parades, speeches, and various cultural events across Greece and in Greek communities worldwide. People often display the national flag and sing the national anthem, honoring those who fought for Greece's freedom and sovereignty during the war.