In May 1745 Charles Edward Stuart wrote of Drummond that it was "impossible that he can escape having his throat cut, for he is dayly affronting people," but during the 1745 Rising he proved to be a reliable and experienced officer.

[3] 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".

[3] 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 further source of recruits was among deserters from the British Army on the Continent and the regiment eventually included men from England and Ireland in addition to those of Scottish or French origin.

Not all units sent by the French were able to pass through the British blockade; one company (including MacDonnell of Glengarry) was captured with L'Esperance off the Dogger Bank, but Drummond and the remainder, under cover of a gale, were able to reach Montrose on 7 December.

Back on the Continent, John Drummond served at the Siege of Bergen op Zoom in July–September 1747, where he was Brigadier in command of the piquets in the trenches; his regiment however does not seem to have joined him, being first recorded in October as part of the Armee de Saxe at Nieuport.

[11] Several other prominent Jacobite exiles also continued to serve as officers, amongst them Ewen MacPherson of Cluny, Donald MacDonnell of Lochgarry and Archibald Cameron of Lochiel, who was captain of the regiment's grenadier company.