Edward George Villiers Stanley, 17th Earl of Derby,, styled Mr Edward Stanley until 1886, then The Hon Edward Stanley and then Lord Stanley from 1893 to 1908, was a British soldier, Conservative politician, diplomat and racehorse owner. He was twice Secretary of State for War and also served as British Ambassador to France.

The Secretary of State for War, commonly called War Secretary, was a secretary of state in the Government of the United Kingdom, which existed from 1794 to 1801 and from 1854 to 1964. The Secretary of State for War headed the War Office and was assisted by a Parliamentary Under-Secretary of State for War, a Parliamentary Private Secretary who was also a Member of Parliament (MP), and a Military Secretary, who was a general.