British field marshal, an outstanding combat leader in the Second Afghan War (1878–80) and the South African War (1899–1902), and the last commander in chief of the British Army (1901–04; office then abolished). Foreseeing World War I, he was one of the earliest advocates of compulsory military service.

Roberts first distinguished himself during the suppression of the Indian Mutiny (1857–58). On Sept. 1, 1880, he scored the decisive victory of the Second Afghan War, defeating Ayub Khan's Afghan Army near Qandahār. From 1885 to 1893 he was commander in chief in India. As the second British commander in chief (December 1899–November 1900) in the South African War, he ended a succession of British defeats; captured Bloemfontein, capital of the Orange Free State Republic (March 13, 1900), and annexed that Boer state as the Orange River Colony (May 24); took the cities of Johannesburg (May 31) and Pretoria (June 5); and defeated Boer commandos at Bergendal (August 27). A field marshal from 1895, he gave way to Horatio Herbert Kitchener as commander in chief in South Africa in November 1900.

Roberts was created a baron in 1892 and an earl and viscount in 1901. Both of his sons having predeceased him, the barony became extinct, but the earldom and viscounty devolved, in turn, on his elder and younger surviving daughters.