By August 1745, the regiment consisted of twenty companies of men. Loudon's regiment was an entirely different unit to the eighteen Independent Highland Companies with whom they are often confused, and which were raised by Duncan Forbes of Culloden starting in October 1745.
The regiment was raised at Inverness and Perth in August 1745 and the Earl of Loudoun served as its colonel throughout its short life. By 8 June 1745, the regiment numbered 1,250 men who were formed into twelve companies.