 Beresford was the fourth son of George Beresford, 1st Marquess of Waterford, by his wife Elizabeth Monck, daughter of Henry Monck.Henry Beresford, 2nd Marquess of Waterford and Lord John Beresford were his elder brothers and Lord Beresford and Sir John Beresford his half-brothers.Beresford was appointed a cornet in the 13th Light Dragoons in April 1794, a lieutenant in the 111th Regiment of Foot in July 1794 and a captain in the 124th Regiment of Foot on 24 September 1794, from which he exchanged into the 88th Regiment of Foot on 29 July 1796.