Two days after the affair of Villiers-en-Couché, Wilson was engaged with his regiment in the action at Cateau (26 April). He also took part in the battle of Tournay, or the Marque, on 10 May; in the capture of Lannoy, Roubaix, and Mouveaux on the 17th; in the disastrous retreat on the 18th to Templeuve, when he commanded the rearguard, and when the light cavalry, according to an eye-witness, ‘performed wonders of valour’ (BROWN, Journal); at the battle of Pont à Chin on 22 May; and at the action of Duffel on 16 July. He greatly distinguished himself in September at Boxtel-on-the-Dommel, when, with Captain Calcraft and the patrol, he penetrated to the French headquarters, captured an aide-de-camp of General Vandamme and two gendarmes, mounted them on the general's horses, and, notwithstanding that a regiment of red hussars and a regiment of dragoons pursued for six miles by separate roads to cut him off, made good his retreat with the captives; and on the same evening falling in with a party of French infantry cut it to pieces. The British army having retreated into Germany, Wilson returned to England at the end of 1795, and joined the depôt at Croydon in February 1796.
He was promoted to be lieutenant, by purchase, on 31 Oct. 1794, and on 21 Sept. 1796 he purchased his troop. He married in 1797, and in May 1798 accompanied Major-general St. John to Ireland, and served as brigade-major on his staff, and afterwards as aide-de-camp during the rebellion of 1798. He rejoined his regiment in 1799, and accompanied it to the Helder; in this campaign the 15th light dragoons were greatly distinguished at Egmont-op-Zee on 2 Oct. Wilson also took part in the actions of 6 and 10 Oct., and returned with the regiment to England in November.
On 28 June 1800 he purchased a majority in Hompesch's mounted riflemen, then serving under Sir Ralph Abercromby in the Mediterranean, and in the autumn travelled across the continent to Vienna on a mission to Lord Minto, by whom he was sent to the Austrian army in Italy. Having communicated with General Bellegarde and Lord William Bentinck, he proceeded to join Abercromby. He landed at Aboukir Bay on 7 March 1801, and took part in the action of the 13th and in the battle of Alexandria on the 21st, when Abercromby fell and was succeeded by Major-general (afterwards Lord) Hutchinson; the latter employed Wilson on several missions. In July he entered Cairo with Hutchinson, was at the siege of Alexandria in August, and its capitulation on the 25th. Wilson left Egypt on 11 Sept. and returned to England by Malta and Toulon, arriving at the end of December. He was made a knight of the order of the Crescent of Turkey for his services in Egypt.
In 1802 Wilson published ‘The History of the British Expedition to Egypt’ (l.p. 4to), which went through several editions, was translated into French in 1803 from an octavo edition in two volumes published that year, and also appeared in an abridged form. The fourth edition in 1803 contained ‘A Sketch of the Present State of the Country and its Means of Defence,’ with a portrait of Sir Ralph Abercromby. Lord Nelson wrote a characteristic letter to Wilson, on receipt of a presentation copy, which is printed in Randolph's ‘Life of Nelson.’ The work derived especial popularity from the charges of cruelty which it brought against Buonaparte, both towards his prisoners at Jaffa and his own soldiers at Cairo. Of these charges the emperor complained to the British government, but, receiving no satisfaction, caused a counter report to be issued by Colonel Sebastiani. Wilson was appointed inspecting field-officer in Somerset and Devonshire under General Simcoe.
In 1804 Wilson published an ‘Inquiry into the Present State of the Military Force of the British Empire with a View to its Reorganization,’ 8vo, in which he made his first public protest against corporal punishment in the army, and was complimented by Sir Francis Burdett in a letter dated 13 Aug. 1804 for the service thus rendered to humanity.
Wilson purchased a lieutenant-colonelcy in the 19th light dragoons in this month, and on 7 March 1805 exchanged into the 20th light dragoons. He sailed with 230 of them in the expedition under Sir David Baird and Sir Home Popham on 27 Aug. from Cork harbour for the Cape of Good Hope, and after a voyage to Brazil, where he purchased horses for the cavalry, and a narrow escape from shipwreck, disembarked with General Beresford on 7 Jan. 1806 in Saldanha Bay, Cape of Good Hope, as an advanced guard. After the battle of Blaauwberg, which took place just before his arrival, Wilson was employed in command of the cavalry on outpost duty until the terms of the capitulation were settled, and in receiving arms, colours, guns, and horses at Simon's Bay until General Janssen and the Dutch troops were deported in February. In June he obtained leave of absence and returned to England in the Adamant, but was nearly lost at sea in passing from one ship to another of the fleet.
