A number of Scottish exiles were already in French service in the Irish Brigade, including Drummond, who held the rank of captain. However, further recruitment in Scotland proved difficult as many Scots disliked serving under Irish officers, joining Dutch regiments for preference. The French government accordingly made formation of a Scots regiment a key element of its plan for a possible campaign in Scotland, with an intention to "confer captaincies on those Highland chiefs known to be loyal to the House of Stuart". A narrative written by "A.M." or "Pickle the Spy", a British intelligence agent now thought to have been Alastair Ruadh MacDonnell of Glengarry, claims that he was responsible for the regiment's formation when he was presented to Louis XV after Dettingen. "A.M." also suggested that Sir Hector Maclean was intended to be Lieutenant-Colonel, but Drummond "got a stop to [his] obtaining the Commission". An ordnance to raise the regiment was dated 3 December 1743; France declared war on Britain in March 1744, and the regiment's first commissions were issued on 1 August.