The Annexation of Hyderabad (code-named Operation Polo) was a military operation launched in September 1948 that resulted in the annexation of the princely state of Hyderabad by India, which was dubbed a "police action".
At the time of partition of India in 1947, the princely states of India, who in principle had self-government within their territories, were subject to subsidiary alliances with the British, which gave control of external relations to the British. 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. The Nizam was also beset by the Telangana rebellion, which he was unable to crush.