Irwin, Sir John (1728–88), soldier and politician, was born in Dublin, only son of Gen. Alexander Irwin, colonel of the 5th Foot, who was well connected politically and a friend of the lord lieutenant of Ireland, the duke of Dorset (qv). As a result of this connection Irwin was made a page of honour at Dublin castle in 1735. His career in the army also started at a young age and, again due to his father's influence, he was commissioned as an ensign in the 5th Foot (July 1736) while only 8 years old. Promoted to lieutenant (January 1737), he took a year's leave in 1748 to travel around Europe before returning to Dublin.
In 1751 he was promoted to major and with the new commanding officer of the 5th Foot, Lt-col. Charles Whitefoord, instigated a number of regimental reforms, even forcing some difficult and lazy officers to resign or exchange into another regiment. He also occasionally served on the staff of the earl of Rothes, then commander-in-chief in Ireland. In 1752 he was made lieutenant-colonel in command of the 5th Foot, and during the Seven Years War he served in France and was present at the battles of Saint-Malo and Saint-Lunaire and the capture of Cherbourg in August 1758. He later served with Prince Ferdinand of Brunswick during his campaign in Germany in 1760. In March 1761 he was promoted to full colonel and given command of the 74th Foot. Promoted to major-general in July of the following year, he subsequently served as governor of Gibraltar (1766–8) and commander-in-chief in Ireland (May 1775–1782). He was also appointed colonel of the 57th Foot and later the 3rd Carabineers.
Irwin's series of rapid promotions owed much to his political connections. Alongside the duke of Dorset, he had become a close friend of Lord Chesterfield (qv), frequently visiting him at Bath, and an associate of George III. In 1762 he entered the British house of commons as member for East Grinstead, a seat in the control of the duke of Dorset. He aligned himself with Lord North's administration (1770–82), and in 1781 initially denied the reports coming from America of Cornwallis's (qv) surrender at Yorktown, in an effort to support another friend, Lord George Germain, the American secretary. In 1779 he was created a Knight of the Bath. Voting with the government in the parliamentary debates of 1782, he resigned from his position as commander-in-chief of Ireland when North's administration fell (March). He was made a full general in February 1783.
Irwin now found himself in financial difficulties, as he had entertained his friends and political colleagues lavishly while in office. Resigning his parliamentary seat in May 1783, he initially settled in Normandy before moving to Parma, Italy. He became a friend of the duke of Parma and died at Parma in late May 1788.
He married three times: first (December 1749) Elizabeth (d. April 1750), daughter of Hugh Henry of Straffan, Co. Kildare; second (1753) Anne (d. 1767 at Gibraltar), daughter of Sir Edward Barry (qv); and later Caroline (surname unknown; d. August 1805). In 1781 Francis Wheatley (qv) painted Irwin while on a tour of Ireland. This painting, entitled ‘General Sir John Irwin at a review in the Phoenix Park’, is in the National Portrait Gallery in London. There is a large collection of his correspondence in the Stopford-Sackville manuscripts.