Operation Polo was the code name of the Hyderabad "police action" in September 1948, by the then newly independent Dominion of India against Hyderabad State. It was a military operation in which the Indian Armed Forces invaded the Nizam-ruled princely state, annexing it into the Indian Union.At the time of Partition in 1947, the princely states of India, who in principle had self-government within their own territories, were subject to subsidiary alliances with the British, giving them control of their external relations. With the Indian Independence Act 1947, the British abandoned all such alliances, leaving the states with the option of opting for full independence. However, by 1948 almost all had acceded to either India or Pakistan. One major exception was that of the wealthiest and most powerful principality, Hyderabad, where the Nizam, Mir Osman Ali Khan, Asaf Jah VII, a Muslim ruler who presided over a largely Hindu population, chose independence and hoped to maintain this with an irregular army.: 224  The Nizam was also beset by the Telangana uprising, which he was unable to subjugate.: 224 In November 1947, Hyderabad signed a standstill agreement with the Dominion of India, continuing all previous arrangements except for the stationing of Indian troops in the state. Fearing the establishment of a Communist state in Hyderabad and the rise of militant Razakars, India invaded the state in September 1948 following a crippling economic blockade. Subsequently, the Nizam signed an instrument of accession, joining India.The operation led to massive violence on communal lines, often perpetrated by the Indian Army. The Indian prime minister, Jawaharlal Nehru, appointed a commission known as the Sunderlal Committee. Its report, which was not released until 2013, concluded that "as a very reasonable & modest estimate...the total number of deaths in the state...somewhere between 30,000 & 40,000." Other responsible observers estimated the number of deaths to be 200,000 or higher.