Henry John Temple, 3rd Viscount Palmerston

Henry John Temple, 3rd Viscount Palmerston (20 October 1784 – 18 October 1865), known as Lord Palmerston, was a British Anglo-Irish politician who served as prime minister of the United Kingdom from 1855 to 1858 and from 1859 to his death in 1865. A member of the Tory, Whig and Liberal parties, Palmerston was also the first Liberal prime minister. An ideologue of "Free-Trade" and a major sponsor of the Opium Wars against the Chinese Empire and the war against Egypt, he dominated British foreign policy from 1830 to 1865 when Britain stood at the height of its imperial power.

In 1802, Temple succeeded to his father's Irish peerage as the 3rd Viscount Palmerston. This Irish peerage did not entitle him to a seat in the House of Lords and Temple became a Tory MP in the House of Commons in 1807. From 1809 to 1828, he was Secretary at War, organising the finances of the army. He was Foreign Secretary from 1830–1834, 1835–1841 and 1846–1851, responding to a series of conflicts in Europe.

In 1852, Palmerston became Home Secretary in the government of the Earl of Aberdeen. As home secretary, Palmerston enacted various social reforms, although he opposed electoral reform. When Aberdeen's coalition fell in 1855 over its handling of the Crimean War, Palmerston was the only man able to sustain a majority in Parliament, and he became prime minister. He had two periods in office, 1855–1858 and 1859–1865, before his death in 1865 at the age of 80 years. Palmerston is considered to have been the "first truly popular" prime minister. He remains the most recent British prime minister to die in office.

Palmerston masterfully controlled public opinion by stimulating British nationalism. He was distrusted by Queen Victoria and most of the political leadership, but he received and sustained the favour of the press and the populace. Historians rank Palmerston as one of the greatest foreign secretaries, due to his handling of great crises, and commitments to the balance of power and British interests. His policies in relation to India, China, Italy, Belgium and Spain had extensive long-lasting beneficial consequences for Britain. However, Palmerston's leadership during the Opium Wars was questioned and denounced by other prominent statesmen. The consequences of the conquest of India have also been reconsidered with time.