Operation Polo was the code name of the Hyderabad "police action" in September 1948, by the then newly independent India against the Hyderabad State. It was a five day military operation in which the Indian Armed Forces invaded the Nizam-ruled princely state, annexing it into the Indian Union. The Instrument of Accession is a legal document executed by Maharaja Hari Singh, ruler of the princely state of Jammu and Kashmir, on 26 October 1947