Henry John Temple, 3rd Viscount Palmerston, (20 October 1784 - 18 October 1865) was a British statesman who was twice Prime Minister in the mid-19th century. Palmerston dominated British foreign policy during the period 1830 to 1865, when Britain stood at the height of its imperial power. He held office almost continuously from 1807 until his death in 1865.