British India consisted of 17 provinces and 562 princely states. The provinces were given to India or Pakistan, in some cases in particular — Punjab and Bengal — after being partitioned. The princes of the princely states, however, won the right to either remain independent or join either nation. Thus India's leaders faced the prospect of inheriting a nation fragmented between medieval-era kingdoms and provinces organized by colonial powers. Out of the 17 provinces, 1 opted out of voting. Under the leadership of Sardar Vallabhbhai Patel, the new Government of India employed political negotiations backed with the option (and, on several occasions, the use) of military action to ensure the primacy of the Central government and of the Constitution then being drafted.
There were three States that proved more difficult to integrate than others:
Junagadh (Hindu majority state with a Muslim nawab) – a December 1947 plebiscite resulted in a 99% vote[8] to merge with India, annulling the controversial accession to Pakistan, which was made despite the people of the state being overwhelmingly Hindu.
Hyderabad (Hindu majority state with a Muslim nizam)– Patel ordered the Indian army to depose the government of the Nizam after the failure of negotiations, which was done between 13–17 September 1948. It was incorporated as a state of India the next year.
The area of Kashmir (Muslim majority state with a Hindu king) in the far north of the subcontinent quickly became a source of controversy that erupted into the First Indo-Pakistani War which lasted from 1947 to 1949. Eventually a United Nations-overseen ceasefire was agreed that left India in control of two thirds of the contested region. Jawaharlal Nehru initially agreed to Mountbatten’s proposal that a plebiscite be held in the entire state as soon as hostilities ceased, and a UN-sponsored cease-fire was agreed to by both parties on Jan. 1, 1949. No statewide plebiscite was held, however, for in 1954, after Pakistan began to receive arms from the United States, Nehru withdrew his support. The Indian Constitution came into force in Kashmir on 26 January 1950 with special clauses for the state.