Major-General Johnston having been removed to the 11th Dragoons, His Majesty conferred the Colonelcy of the First Horse on Major-General James Johnston (cousin of the former colonel of the same name), from the Ninth Dragoons, by commission dated the 27th of April, 1775.
1776
The British colonies in North America having rebelled against the mother-country, the regiment furnished in February, 1776, a draft of sixteen troop-horses to be sent to North America and employed in that country as the service required; 180 horses were sent from the cavalry corps in Ireland, and 16 guineas were allowed to the regiment for each horse. In July an augmentation of one corporal and 10 private men per troop was made to the establishment; parties of mounted men were sent out to enlist recruits, and directions were given that none but Protestants be engaged.
1777
1778
In the beginning of 1777 the regiment was again in cantonments in the country, the head-quarters being at Castlebar, from whence they were removed in June to Roscommon, &c., but returned to Castlebar in the winter, and in May, 1778, proceeded to Birr, where the regiment was reviewed, on the 24th of that month, by Major-General De Burgh. While at this station the officers were ordered to provide themselves with tents, and to be in constant readiness to take the field. In June the head-quarters were removed to Belfast, in July to Armagh, and in September returned to Belfast.
In April, 1778, Lieutenant-General James Johnston was removed to the Enniskillen Dragoons, and was succeeded in the command of the First Horse by Major-General George Warde, from the 14th Dragoons.
1779
1780
1781
On the 1st of June, 1779, the regiment marched to Lisburn, and in July the head-quarters were established at Belturbet. At this station they appear to have remained until July, 1781, when they were removed to Athlone, where the regiment was reviewed by Major-General Massey on the 2nd of August, and soon afterwards proceeded to Dublin, but in November returned to Athlone.
1782
1783
The regiment was again reviewed by Major-General Massey, on the 21st of June, 1782, at Athlone, from whence it marched, in a few days afterwards, to Mount Mellick, and, in January of the following year, to Dublin.