Greek Independence Day, national holiday celebrated annually in Greece on March 25, commemorating the start of the War of Greek Independence in 1821. It coincides with the Greek Orthodox Church’s celebration of the Annunciation to the Theotokos, when the Archangel Gabriel appeared to Mary and told her that she would bear the son of God.
In celebration of Greek Independence Day, towns and villages throughout Greece hold a school flag parade, during which schoolchildren march in traditional Greek costume and carry Greek flags. There is also an armed forces parade in Athens.
Ἀπολυτίκιον Εὐαγγελισμοῦ-Apolytikion Annunciation.
Τη Υπερμάχω Στρατηγώ - To thee, the Champion Leader.
Educational resources here and here. Printable worksheets here and here.