Things moved quickly after the partition of British India in 1947. By the end of 1949, all of the states except Sikkim had chosen to accede to one of the newly independent states of India or Pakistan or else had been conquered and annexed.
For details of precedence between the states, see Salute state.
In principle, the princely states had internal autonomy, while by treaty the British Crown had suzerainty and was responsible for the states' external affairs. In practice, while the states were indeed ruled by potentates with a variety of titles, such as Chhatrapati, Maharaja, Raja, Raje, Deshmukh, Nawab, Baig, Khan, Nizam or Mirza, the British had considerable influence.
The most important states were ranked among the salute states.
By the Indian Independence Act 1947, the British gave up their suzerainty of the states and left each of them free to choose whether to join one of the newly independent countries of India and Pakistan or to remain outside them. For a short time, some of the rulers explored the possibility of a federation of the states separate from either, but this came to nothing. Most of the states then decided to accede to India or to Pakistan, such as Junagadh (1947–1948), Hyderabad on 18 September 1948, Bilaspur on 12 October 1948, and Bhopal on 1 May 1949. Travancore also chose to remain an independent country.
In Jammu and Kashmir, a state with a Muslim majority but a Hindu ruler, the Maharaja hoped to remain independent but acceded to India on 27 October 1947 at the outset of the invasion of Jammu and Kashmir by Pakistan — leading to the Indo-Pakistani War of 1947.
On 31 March 1948, Kalat acceded to Pakistan, although the brother of the Khan led a rebellion against this decision.
The last remaining independent state, Sikkim, was incorporated into India on 16 May 1975, following a referendum in which the people of Sikkim overwhelmingly voted for this.
Indian Princely States at the time of independence on 14 August 1947
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India's Princely States: People, Princes and Colonialism, by Waltraud Ernst, Biswamoy Pati. Published by Routledge, 2007. ISBN 0-415-41541-1.