Lyttelton became assistant military secretary to Lieutenant General Sir John Adye in his role as Governor of Gibraltar on 1 January 1883[9] and military secretary to Lord Reay, Governor of Bombay in 1885.[1] In his young life he made friends, mixing in whiggish aristocratic circles with Edward Grey and Arthur Balfour, later the shapers of imperial foreign policy.[10] He was promoted to brevet colonel on 18 November 1886[11] and became second-in-command of the 3rd Battalion of his regiment in 1890.[1] Promoted to the substantive rank of lieutenant colonel on 9 November 1892,[12] he became commanding officer of the 1st Battalion of his regiment in 1893 and went on to be commanding officer of the 2nd Battalion of his regiment in Ireland.[1]
He went on to be assistant adjutant-general at Headquarters in December 1894 and assistant military secretary there in October 1897[1] and took part in the state funeral of Former prime ministerWilliam Gladstone in May 1898.[13]
Lyttelton returned to his role as assistant military secretary at headquarters on 21 October 1898[15] and then, having become a supernumerary major general for distinguished service in the field on 15 November 1898[16] and promoted to the substantive rank of major general on 10 February 1899,[17] he briefly took back his old command at 2nd Brigade, now based at Aldershot Command, on 1 September 1899.[18]
Lyttelton served in the Second Boer War as commander of the 4th Brigade in South Africa from 9 October 1899.[19] He temporarily became general officer commanding the 2nd Division in February 1900,[20][21] then commanded the 4th Division,[22] and was involved in the Battle of Spion Kop in January 1900 and the Battle of Vaal Krantz in February 1900, leading to the Relief of Ladysmith later that month.[1] Promoted to lieutenant general for distinguished service in the field on 22 March 1900,[23]Lord Roberts in his despatch referred to Lyttelton as an officer "with great coolness under fire, and considerable tactical knowledge and resource...an excellent commander in the field."[24] He was in command of the troops in Natal until June 1902, when he became Commander-in-Chief of the whole of South Africa following the end of the Second Boer War the previous month.[25][26] In this role Lyttelton and his wife sought to repair relations with the Boer community.[1] In the South Africa honours list published on 26 June 1902, Lyttelton was knighted as a Knight Commander of the Order of the Bath (KCB).[27]
In 1883 Lyttelton married Katharine Sarah Stuart-Wortley, the youngest of the nine children of the politician James Stuart-Wortley and Jane Lawley. They had three daughters:[37]
Hilda Margaret Lyttleton (1886–1972), who married Arthur Morton Grenfell and had four children, including Mary (mother of William Waldegrave), Frances and Laura (the wife of Lord Ballantrae)
Mary Hermione Lyttleton (1894–), who married the businessman Lionel Hichens and had six children, including Stella (wife of Richard Hornby) and Andrew[38]