He went out a fourth time to the same station in 1801, and served there till 1804. In 1805 he was appointed to the permanent staff of the quartermaster-general's department, and served as an assistant quartermaster-general in Kent, under Generals Sir John Moore and Francis Dundas, and also with the Copenhagen expedition of 1807. In 1808 he brought out a reprint of the French text of Count L'Espinasse's ‘Essai sur l'Artillerie’ (Paris, 1800). It was printed by Rouse, Kirby, & Lawrence of Canterbury, and was translated into English forty years afterwards by Major P. J. Begbie, Madras artillery. In 1809 Donkin was appointed assistant quartermaster-general with the army in Portugal, and as a colonel on the staff commanded a brigade in the operations on the Douro and at the battle of Talavera, but soon returned home (see Gurwood, Well. Desp. iii. 262, 298, 373; compare with Parl. Hist., 3rd ser. xvii. 55), and was appointed quartermaster-general in Sicily in succession to Colonel H. E. Bunbury [see Bunbury, Sir Henry Edward]. He served in that capacity in Sicily, and in the operations on the east coast of Spain in 1810–13, and at the moment was blamed as the cause of Sir John Murray's disaster at Tarragona in the latter year, but the evidence on Murray's court-martial showed that the latter had ignored his quartermaster-general altogether, and disregarded his views (see Napier, Hist. Penins. War, book xx. cap. 1). Donkin, who had become major-general in 1811, was next appointed to a command in the Essex district, and in July 1815 to one at Madras, whence he was afterwards transferred to the Bengal presidency. Before leaving England he married, 1 May 1815, Elizabeth, eldest daughter of Dr. Markham, dean of York, and granddaughter of Archbishop Markham (see Lives of the Markhams, privately printed, 1854, p. 51). Donkin commanded the 2nd field division of the grand army under the Marquis of Hastings in the operations against the Mahrattas in 1817–18, and by skilful movements cut off the line of retreat of the enemy towards the north (see Lond. Suppl. Gaz. 25 Aug., 26 Sept. 1818; also Gent. Mag. lxxxix. i. 73–8, 262–3). Donkin's letters to Colonel Nicol and the Marquis of Hastings at this time form Brit. Mus. Add. MS. 23759. He was made K.C.B. 14 Oct. 1818. While employed as above he had the misfortune to lose his wife, who died at Meerut, at the age of twenty-eight, on 21 Aug. 1818, leaving him with an infant son. Much shattered in health, bodily and mentally, Donkin was invalided to the Cape. While there in 1820 he was requested to assume the government of the colony during the absence of Lord Charles Somerset. He administered it in 1820–1, his name being meanwhile retained on the Bengal establishment. This was the period of the settlement of the eastern frontier, and the now thriving town on the shore of Algoa Bay was named by Donkin Port Elizabeth, after his late wife. He seems to have been popular, but was not supported by Earl Bathurst, the colonial minister. In a letter addressed to that nobleman, and entitled ‘A Letter on the Cape of Good Hope, and certain events which occurred there under Lord Charles Somerset’ (London, 1827), Donkin published ‘an account of the measures adopted by me generally in my administration of the colony of the Cape of Good Hope, but particularly as to my measures for establishing five thousand settlers in that colony, and those pursued by Lord Charles Somerset for the total subversion of all I had done under your lordship's instructions.’ A printed volume of ‘Proclamations and other Official Documents issued by Sir Rufane Donkin when Acting Governor of the Cape of Good Hope’ is in the Brit. Mus. Library. Donkin, who had become a lieutenant-general in 1821, was made G.C.H. some time after his return from the Cape, ‘in recognition of his services at various times in connection with the German Legion.’ He was made colonel of the 80th foot in 1825.
The rest of Donkin's life was principally devoted to literary and parliamentary pursuits. He was made F.R.S., was one of the original fellows of the Royal Geographical Society, and a fellow of other learned societies. He was a contributor to various periodicals, among others to the ‘Literary Gazette’ (see Lit. Gaz. 1841, p. 301); but the statement (Gent. Mag. new ser. xvi. 318) that he wrote in the ‘Quarterly Review’ appears to be incorrect, as it is stated on the best authority that he never wrote a line there. Donkin published ‘A Dissertation on the Course and probable Termination of the Niger’ (London, 1829, 8vo), dedicated to the Duke of Wellington, in which he argued, chiefly from ancient writers, that the Niger was a river or ‘Nile’ bearing northwards, and probably losing itself in quicksands on the Mediterranean shore (in the Gulf of Sidra, according to the subsequent ‘Letter to the Publisher’). This view was refuted in the ‘Quarterly Review,’ lxxxi. (1829), in an article by Sir John Barrow [q. v.], who testified, from personal knowledge, that Donkin was ‘an excellent scholar, of a clear, logical, and comprehensive mind, vigorous in argument, and forcible in language,’ and that ‘consequently whatever proceeds from his pen will always be entitled to respect and most
