At the time of Indian independence in 1947, India was divided into two sets of territories, one under direct British rule, and the other under the suzerainty of the British Crown, with control over their internal affairs remaining in the hands of their hereditary rulers, and control over external affairs and defence being vested in the Government of India under the Viceroy. In addition, there were several colonial enclaves controlled by France and Portugal. The political integration of these territories into India was a declared objective of the Indian National Congress, and the Government of India pursued this over the next decade. Through a combination of factors, Sardar Vallabhbhai Patel and Jawaharlal Nehru convinced the rulers of the various princely states to accede to India. Having secured their accession, they then proceeded, in a step-by-step process, to secure and extend the central government's authority over these states and transform their administrations until, by 1956, there was little difference between the territories that had been part of British India and those that had been part of princely states. Simultaneously, the Government of India, through a combination of diplomatic and military means, acquired de facto and de jure control over the remaining colonial enclaves, which too were integrated into India.
Although this process successfully integrated the vast majority of princely states into India, it was not as successful for a few, notably the former princely states of Jammu and Kashmir, Tripura and Manipur, where active secessionist movements exist.
The early history of British expansion in India was characterised by the co-existence of two approaches towards the existing princely states. The first was a policy of annexation, where the British sought to forcibly absorb the Indian princely states into the provinces which constituted their Empire in India. The second was a policy of indirect rule, where the British assumed suzerainty and paramountcy over princely states, but conceded to them sovereignty and varying degrees of internal self-government. During the early part of the 19th century, the policy of the British tended towards annexation, but the Indian Rebellion of 1857 forced a change in this approach, by demonstrating both the difficulty of absorbing and subduing annexed states, and the usefulness of princely states as a source of support. In 1858, the policy of annexation was formally renounced, and British relations with the remaining princely states thereafter were based on subsidiary alliances, whereby the British exercised paramountcy over all princely states, with the British crown as ultimate suzerain, but at the same time respected and protected them as allies, taking control of their external relations. The exact relations between the British and each princely state were regulated by individual treaties and varied widely, with some states having complete internal self-government, others being subject to significant control in their internal affairs, and some rulers being in effect little more than the owners of landed estates, with little autonomy.