Hugh Sempill, 12th Lord Sempill was a Scottish soldier. He was the fifth son of Francis Abercromby, Lord Glasfoord by his wife Anne Sempill, 9th Lady Sempill, daughter of Robert Sempill, 7th Lord Sempill. On 17 February 1727 he succeeded his brother as Lord Sempill, and that year he sold the estates of Elliotstoun and Castle Sempill, purchasing the estate of North Barr in 1741. He went early into the Army, and was adjutant to Colonel Preston's Regiment of Foot1 December 1708, ensign in the same regiment July 1709, and served at the Battle of Malplaquet. He was promoted captain 12 July 1712 and was placed on half-pay in 1713. In 1715 he was appointed captain in Brigadier-General Grant's Regiment, and promoted major on 5 April 1718. Sempill was made lieutenant-colonel of the 19th Regiment of Foot on 12 July 1731, and succeeded the Earl of Crawford as colonel of the Black Watch on 14 January 1741. He was in command when the regiment mutinied in 1743, and followed them that year to Flanders, where they highly distinguished themselves. He received a "warrant under the sign manual of the Lords Justices, countersigned by the Treasury Lords being respective allowances to enable the officers belonging to the corps under their command to provide themselves with baggage horses upon their going to Flanders."Roxine A. Beaumont-Sempill The Semples, Lord Sempills of West Scotland: family and contextual history from the 11th to 19th Centuries, pg 196. Cites William A. Shaw, Calendar of Treasury Books and Papers, Volume 5, 1742-1745, pp. 268-281. and uses Lawrence H. Officer and Samuel H. Williamson Five Ways to Compute the Relative Value of a UK Pound amount, 1270 to Present. He commanded in the town of Aeth when it was besieged by the French, and that regiment made a gallant defence. He was appointed colonel of the 25th Regiment of Foot on 9 April 1745 and promoted brigadier-general 9 June 1745. He was present at the Battle of Culloden on 16 April 1746, when he had command of the left wing of the royal army. In the middle of August following he arrived at Aberdeen and assumed the command of the troops stationed in that quarter, but died there on 25 November 1746. His remains were interred in the Drum Aisle in the West Church of that city on 1 December following. Lord Sempill had been married on 13 May 1718 to Sarah, daughter of Nathaniel Gaskell of Manchester. They had five sons, including John Sempill, 13th Lord Sempill, and six daughters, the eldest of whom, Sarah, married Patrick Crauford MP. Lady Sempill died on 17 April 1749. A portrait of Hugh, 12th Lord Sempill can be seen in a new Sempill history.
