Task: Question Generation
Input (English): Context : The Battle of Navarino was a naval battle fought on 20 October 1827, during the Greek War of Independence (1821--32), in Navarino Bay (modern-day Pylos), on the west coast of the Peloponnese peninsula, in the Ionian Sea. 
Answer : 20 October 1827
Output (English): When did Battle of Navarino occur?