Lord Eustace Brownlow Henry (Gascoyne-)Cecil (24 April 1834 – 3 July 1921) was a British, Conservative Party politician. Cecil was the youngest son of James Gascoyne-Cecil, 2nd Marquess of Salisbury by his first wife Frances Gascoyne and was educated at Harrow and the Royal Military College, Sandhurst. He served with the Coldstream Guards in the Crimean War from 1855 to 1856, rose to the rank of Lieutenant Colonel in 1861 and retired from the army in 1863. On 18 September 1860, he had married Lady Gertrude Scott (the fourth daughter of John Scott, 2nd Earl of Eldon) and they had three children: Evelyn, later 1st Baron Rockley (1865–1941), Algernon (1879–1953) and Blanche Louise (1872–1945).