The best known phrase associated with the British Empire from the middle of the nineteenth century until the early twentieth was that "the sun never set" over its dominions. That was, quite literally, true. Roughly 25% of the surface of the globe was directly or indirectly controlled by the British in the aftermath of World War I (1918). Enormous bureaucracies of "natives" worked under white British officials everywhere from the South Pacific to North Africa. The ultimate expression of British imperialism was in India, where just under 100,000 British officials governed a population of some 300,000,000 Indians.
Until 1857, India was governed the British East India Company (the EIC), the state-sponsored monopoly established in the seventeenth century to profit from overseas trade and which controlled a monopoly on Indian imports and exports. Through a long, slow creep of territorial expansion and one-sided treaties with Indian princes, the EIC governed almost all of the Indian subcontinent by 1840. India produced huge quantities of precious commodities, including cotton, spices, and narcotics. In fact, the EIC was the single largest drug cartel in world history, with the explicit approval of the British government. Most of those narcotics consisted of opium exported to China.
By the 1830s, 40% of the total value of Indian exports took the form of opium, which led to the outbreak of the first major war between a European power, namely Britain, and the Chinese Empire. In 1840, Chinese officials tried to stop the ongoing shipments of opium from India and open war broke out between the EIC, supported by the British navy, and China. A single British gunboat, the Nemesis, arrived after inconclusive fighting had gone on for five months. In short order, the Nemesis began an ongoing rout of the Chinese forces. The Chinese navy and imperial fortresses were nearly helpless before gunboats with cannons, and steamships were able to penetrate Chinese rivers and the Chinese Grand Canal, often towing sailing vessels with full cannon batteries behind them.
In the end, the Royal Navy forced the Chinese state to re-open their ports to the Indian opium trade, and the British obtained Hong Kong in the bargain as part of the British Empire itself. In the aftermath of the Opium War, other European states secured the legal right to carry on trade in China, administer their own taxes and laws in designated port cities, and support Christian missionary work. The authority of the ruling Chinese dynasty, the Qing, was seriously undermined in the process. (A second Opium War occurred in the late 1850s, with the British joined by the French against China - this war, too, resulted in European victory.)
Trouble for the British was brewing in India, however. In 1857, Indian soldiers in the employ of the EIC, known as sepoys, were issued new rifles whose bullet cartridges were, according to rumors that circulated among the sepoys, lubricated with both pig fat and cow fat. Since part of loading the gun was biting the cartridge open, this would entail coming into direct contact with the fat, which was totally forbidden in Islam and Hinduism (note that there is no evidence that the cartridges actually were greased with the fat of either animal - the rumors were enough). Simultaneously, European Christian missionaries were at work trying to convert both Muslims and Hindus to Christianity, sometimes very aggressively. This culminated in an explosion of anti-Christian and anti-British violence that temporarily plunged India into a civil war. The British responded to the uprising, which they dubbed “The Mutiny” by massacring whole villages, while sepoy rebels targeted any and all British they could find, including the families of British officials. Eventually, troops from Britain and loyal Sepoy forces routed the rebels and restored order.
After this Sepoy Rebellion (the term that has long since replaced “The Mutiny” among historians), the East India Company was disbanded by the British parliament and India placed under direct rule from London. India was henceforth referred to as the "British Raj," meaning British Rulership, and Queen Victoria became the Empress of India in addition to Queen of Great Britain. She promised her Indian subjects that anyone could take the civil service examinations that entitled men to positions of authority in the Indian government, and elite Indians quickly enrolled their sons in British boarding schools. The first Indian to pass the exam (in 1863) was Satyendranath Tagore, but white officials consistently refused to take orders from an Indian (even if that Indian happened to be more intelligent and competent than they were). The result was that elite Indians all too often hit a "glass ceiling" in the Raj, able to rise to positions of importance but not real leadership. In turn, resentful elite Indians became the first Indian nationalists, organizing what later became the Indian independence movement.