Dictionary of National Biography, 1885-1900/Moore, Jonas (1691?-1741)
MOORE, JONAS (1691?–1741), military engineer, probably grandson of Sir Jonas Moore [q. v.] the mathematician, received his commission as probationer engineer in October . On 1 Jan. 1711 he was appointed sub-engineer at Gibraltar and attached to David Colyear, first earl of Portmore [q. v.], the governor, for special ser vice. Later he was sent to Port Mahon, Minorca, where he remained for some years, returning to Gibraltar in August 1720. On 18 Nov. he was appointed chief engineer and commissioned as commander-in-chief of the train of artillery at Gibraltar. He was promoted sub-director of engineers and major on 1 Oct. 1722. He received several letters from the board of ordnance conveying their good opinion of his ability and economy, and in one, dated 22 Jan. 1727, he was informed that his care not to exceed the estimates has been noticed by the master-general and board, and 'gains much their esteem.'
Moore was chief engineer at Gibraltar during the siege by the Spaniards in 1727. The trenches were opened on 11 Feb., and the siege was not raised until 23 June. The Spaniards lost many men, but owing to the excellent cover provided by Moore, who went over to Morocco and visited Tetuan to secure supplies of fascines and brushwood, the British loss was comparatively small. On 19 March 1728 he was given the local rank of director of engineers. He remained at Gibraltar until 1740, and in October of that year was appointed chief engineer with the joint expedition which sailed from Spithead under Rear-admiral Sir Chaloner Ogle and General Lord Cathcart for Spanish America. On arrival at Dominica Lord Cathcart died, and was succeeded by General Wentworth, an incompetent officer. Ogle proceeded to Jamaica, where he joined Vice-admiral Vernon. After many conflicting schemes it was resolved to attack Carthagena, a strongly fortified place, well garrisoned and ably commanded.
Moore erected his batteries on the shore on 9 March 1741, and soon made a breach in Fort St. Louis, a work which mounted eighty-two guns and defended the mouth of the harbour. Moore was, however, struck on the 22nd by a fragment of a shell, and died the following day. His death was a serious blow to the enterprise. The incompetence of the general led to disaster which might have been avoided had the chief engineer survived. As it was, the land forces were re-embarked, and the expedition sailed back to Jamaica. Moore carried a dormant commission by order of the Duke of Montagu, dated 24 July 1740, to command the artillery in the event of the death of the two senior officers of that corps.
There are in the war office twenty plans and sections of Gibraltar and various works of defence in that fortress skilfully drawn by Moore.[Despatches; War Office Records; Royal Engineers' Records; Beatson's Naval and Military Memoirs, 1804, vol. i.; Cust's Annals of the Wars of the Eighteenth Century, 1860.]