John Beresford, whose name is even yet occasionally reproached by the descendants of his political opponents, was born in 1738, and died in 1805. He was the second son of Marcus, Earl of Tyrone (brother of the first Marquess) and Lady Katherine, Baroness de la Poer. Appointed First Commissioner of Revenue in 1780, John Beresford became in fact ruler of Ireland. He was entrusted by Pitt with the management of all Irish affairs. Viceroys came and viceroys went, but Beresford continued to hold a position "greater than that of the Lord Lieutenant { xxix} himself"; much to the indignation of Lord Fitzwilliam, who, when he was appointed Lord Lieutenant, permitted himself to address the First Commissioner in terms so indigestible that Beresford promptly challenged him. The duel, however, was prevented. John Beresford took a great part in the preparation and passing of the Act of Union; was M.P. for Waterford and a Privy Councillor; and did much to improve the city of Dublin, the fine Custom-house being built under his auspices. He married Barbara Montgomery, who was one of the "Three Graces" in the painting done by Sir Joshua Reynolds, now in the National Gallery. The other two Graces were her sister, Lady Mountjoy, and the Marchioness of Townshend.
Admiral Sir John Poo Beresford (1768 (?)-1884) was a natural son of the first Marquess of Waterford. He entered the Royal Navy in 1782; fought a smart action in the capture of the French store-ships in Hampton Roads on 17th May 1795; and performed distinguished service in the West Indies. He took part in the famous eight months' blockade off Ferrol in 1808, and in the blockade of Lorient, commanding one of those "weather-beaten ships upon which the Grand Army never looked." In 1810 he was co-operating off Lisbon with Wellington's army, with which his younger brother the Marshal, in command of the Portuguese Army, was also co-operating. He represented in Parliament, in succession, Coleraine, Berwick, Northallerton, and Chatham. In 1835 he was Junior Lord of the Admiralty. His career, a combination of fighting seaman, member of Parliament, and Junior Lord, presents a singular resemblance to the career of his relative, Lord Charles Beresford.