Between 1817 and 1818, the British army in India fights what is called the Third Marathan War. This sees the final subjugation of the Marathan and Rajput states. In 1815, the British had acquired the colony of Ceylon from the Dutch. By 1820, they controlled almost the whole of what today are Pakistan, India, Bangledesh and Sri Lanka. The political system was confusing. The areas under direct British control were still run by the British East India Company. These were made up of three main provinces or "presidencies", Bombay, Madras and Bengal. Each presidency had its own military force. Those regions not directly controlled by the East India company were administered by a system of alliances with the traditional local rulers. These various princes had little real power and depended on Britain for their position.

The British, worried about Russian influence in Afghanistan invade the country between 1839 and 1842, what is called the First Afghan War. The Afghans had only formed a kingdom less than a hundred years before, and fighting between the warlike Afghan tribes was frequent, but they would fiercely resist attack by any foreign army. The British capture the Afghan capital Kabul, but here they suffer a crushing defeat. An entire army is surrounded and slaughtered at Kabul. The Afghans spare just one British soldier so he can go home and tell everyone about the disaster. In 1849, Britain annexed the Punjab. Raiding from the mountain tribes on the frontier with Afghanistan remained a problem.

Two British soldiers, with an Indian sepoy standing on the right On May 10, 1857, The great Sepoy Rebellion breaks out. Sepoys were Indian troops serving in the British army. Growing discontent with British rule led to the rebellion. The sepoys were initially successful and there were horrible massacres of Europeans. The last Moghul ruler, Bahadur Shah, mostly against his will, was made "emperor of India". The British counter-attack using Sikhs and Gurkhas, and British reinforcements. The rebels are defeated at Delhi and Lucknow and the whole rebellion is put down by the end of 1858. More horrific atrocities are carried out with whosale killings of Indians, whether or nor they were part of the rebellion. One result of the rebellion was the elimination of the East India Company in 1858. All of India now came under direct British colonial rule.