Frederick Sleigh Roberts was the second son of General Sir Abraham Roberts, G.C.B. (1784-1873). He was born at Kanpur (then Cawnpore), India, on the 30 September 1832. Roberts was educated at Eton, Sandhurst and Addiscombe, and he obtained a commission in the Bengal Artillery on 12 December 1851. In the following year he was posted to a field battery at Peshawar, where he also acted as aide-de-camp to his father, who commanded the Peshawar division. Roberts was an outstanding combat leader in the Second Afghan War (1878-80) and the South African War (1899-1902). He became Commander-in-Chief in India (1885-1893), and was the last Commander-in-Chief of the British Army (1901-04) before the office was abolished. He had been made a Field-Marshal in 1895. Foreseeing World War I, he was one of the earliest advocates of compulsory military service.

Roberts had first distinguished himself during the suppression of the Indian Mutiny (1857-58). On September 1, 1880, he scored the decisive victory of the Second Afghan War, defeating Ayub Khan's Afghan Army near Kandahar. In the South African War, he ended a succession of British defeats, and captured Bloemfontein, capital of the Orange Free State Republic on 13 March 1900. He then annexed the state as the Orange River Colony in May 1900, and took the cities of Johannesburg and Pretoria. He gave way to Horatio Herbert Kitchener as Commander-in-Chief in South Africa in November 1900.

Roberts was awarded the Victoria Cross (VC) in December 1858 for actions on 2 January 1858 at Khudaganj, India. He was created a Baron in 1892 and an Earl and Viscount in 1901. Field-Marshal The Rt Hon. The Earl Roberts VC KG KP GCB OM GCSI GCIE PC died from pneumonia at Saint-Omer, France, on 14 November 1914.

The Field-Marshal was one of only two non-Royal persons to lie-in-state in Westminster Hall during the 20th century (the other was Sir Winston Churchill). He was given a State Funeral.