McEwan arrived with the Royal Irish at Philadelphia on 11 July 1767. He served with the Grenadier Company throughout its American Service travelling to Ft. Pitt, Ft. Chartres, Cahokia and then from Philadelphia to New York City before embarking on the Empress of Russia for Boston in October 1774. He would have been on the March to Concord and at Bunker Hill. He was present when mustered on 7 October 1775 at Charles Town Heights.
On 5 December 1775, McEwan was drafted into the 35th Regiment of Foot and received into Capt. Phillip’s Coy. He was present with that company on 25 June 1776 at Staten Island. He was transferred to Cpt. Massey’s Coy on 19 April 1777 while at Brunswick, New Jersey. He was then transferred to the Grenadier Coy for the Philadelphia Campaign which included fighting at the battles of Brandywine and Germantown. He wintered at Philadelphia being still present on 6 February 1778. He returned to New York City and was mustered their on 22 July 1778 with his regiment. That fall, McEwan was embarked for the Caribbean with General Grant’s Command and the 35th Foot fought at St. Lucia in December 1778. He was listed as present on St. Lucia on 10 April and 19 August 1780. No further record of McEwan shows up until he is listed as present at Dorchester, England on 4 August 1783. He was a lucky man to have survived several years of active campaigning as well as the disease ridden climate of the West Indies.