Don was not evacuated with the rest of the British army in 1795 after the campaign's collapse, but instead remained in Europe in the service of the
Prussian King. Prussia had been knocked out of the war following the
Peace of Basel in 1795, but remained allied to Britain in her struggle with France and Don was seconded to the Prussian court as a liaison officer. He may have coordinated espionage activities against France during this period, although records are vague. In 1798 Don returned to Britain as a
major-general and was placed in command of the defences of the
Isle of Wight, a weak spot on the Southern Coast of England. In 1799, he was attached to the force under the
Duke of York which invaded the
Batavian Republic with an Anglo-Russian army. He was ostensibly in command of the 3rd Division under Sir
David Dundas but was frequently detached on espionage and negotiation duties. This culminated in his arrest by
Guillaume Brune during negotiations to allow a peaceful withdrawal of allied troops. Charged with attempting to provoke an anti-French rebellion among the Dutch inhabitants of the Batavian Republic, Don spent the next two years in prison, only being released at the end of 1800 in the prelude to the
Peace of Amiens. While in captivity, he was rewarded with the colonelcy of the
9th West India Regiment. On his release, Don returned to Scotland and in 1802 was in charge of organising and training the militia forces which were tasked with the defence of the South-Eastern coast of Scotland. In 1803 he returned to London to command the
King's German Legion, a
Hanoverian formation seconded to the British Army. Promoted
Lieutenant-General on 1 January 1805, on 5 November of the same year he sailed with a 14,000 strong force to Germany, part of the
Hanover Expedition. Landing at
Cuxhaven 17th he was superseded by
Lord Cathcart soon after his arrival. ==Governor of Jersey and Gibraltar==