Robert Stewart was born to the elder Robert Stewart, 1st Marquess of Londonderry, a landowner who was created an earl and subsequently a marquess by King George III, in Dublin. Even before his father's election to the Irish House of Commons in 1771, this heritage put him squarely in the landed gentry class of Ulster Presbyterians whose ancestors first arrived in Ireland during the Plantation of Ulster.
He received his secondary education at The Royal School, Armagh, and later attended St. John's College, Cambridge for one year.[1] There, he learned Latin in addition to his native English. Later, he learned French, the language of his trade of diplomacy.
In 1790, Stewart was elected as a Member of Parliament for County Down and entered the Irish House of Commons as a Whig on a platform supporting electoral reform and Catholic emancipation. He was, however, enrolled in the militia shortly thereafter as an officer, a matter of course for a young aristocrat, and got to see very little of the Commons. In 1794, he won the English seat of Tregony on a similar platform. In 1795, he crossed the floor to join the Tories, but his initial principles of reform and emancipation continued to hold a place in his political thought.
In 1794, Stewart married Emily Hobart, a woman noted in contemporary accounts for her attractiveness and eccentricity. By all accounts, the two remained devoted to each other to the end, but they had no children. They did, however, care for the young Frederick Stewart, Stewart's nephew, while his father was serving in the army.
By 1797, he had risen to the post of Chief Secretary for Ireland. In this capacity, he played a key role in quashing the Irish Rebellion of 1798, offering clemency to commoners who had supported the rebellion, and focusing instead on pursuing rebel leaders. In 1800, he began lobbying in the Irish and British Parliaments for an official union between the two, convinced that it was the best way to soothe the long-standing sectarian divides in Ireland.
During his campaign for the Act of Union, he had promised that Irish Catholics would be allowed to sit in parliament, a move that was opposed by much of the British establishment, including George III. When it came to light in that the king had approached Henry Addington, an opponent of emancipation, about becoming Prime Minister to replace the pro-emancipation Pitt, both Castlereagh and Pitt resigned in protest.
After a few years, tensions between Tories supporting emancipation and those opposing it had relaxed, and Castlereagh returned to the cabinet as President of the Board of Control. In 1804, after much urging by Castlereagh, Pitt returned as Prime Minister, and Castlereagh was promoted to Secretary of State for War and the Colonies. After Pitt's death in 1806, Castlereagh resigned amidst the chaos of the Ministry of All the Talents. After that cabinet collapsed, Castlereagh again became Secretary of State for War and the Colonies in the Duke of Portland's administration in 1807.
Three years later, in 1812, Castlereagh returned to the government, this time as Foreign Secretary, a role in which he served for the next ten years. He also became leader of the House of Commons in the wake of Spencer Perceval's assassination in 1812. In his role of Foreign Secretary he was instrumental in negotiating what has become known as a quadruple alliance between the United Kingdom, Austria, Russia and Prussia at Chaumont in March 1814, in the negotiation of the Treaty of Paris that brought peace with France, and at the Congress of Vienna.
In the years 1812 to 1822, Castlereagh continued to competently manage Britain's foreign policy, generally pursuing a policy of continental engagement uncharacteristic of British foreign policy in the nineteenth century. Castlereagh was not known to be an effective public speaker and his diplomatic presentation style was at times abstruse. He nonetheless developed a reputation for integrity, consistency and good will, which was perhaps unmatched by any diplomat of that era. His views on foreign policy were, unfortunately for him, ahead of his time.
Despite his achievements, Castlereagh was extremely unpopular domestically as a result of his supposed reactionism abroad, and his association with the repressive measures of the Home Secretary, Lord Sidmouth. He attracted this last criticism because, as the Leader of the House of Commons, he was often called upon to defend government policy in the House. He had to defend the widely reviled measures taken by Sidmouth and the others, including the infamous Six Acts, in order to remain in cabinet and continue his diplomatic work.
After the death of his father in 1821, he became Lord Londonderry. The next year, he began to suffer from a form of paranoia or a nervous breakdown, possibly as a result of an attack of gout and the stress of public criticism and the weak British position at the European Congresses. Londonderry returned to his country seat at Loring Hall in Water Lane, North Cray, Kent on the advice of his doctor.
On 9 August 1822 he had an audience with King George IV in which he revealed to the King that he thought he was being blackmailed. He said, "I am accused of the same crime as the Bishop of Clogher." Percy Jocelyn, the Bishop of Clogher until that July, was prosecuted for homosexuality, and Castlereagh believed he was being blackmailed for the same reason. Whether this was true or a function of his paranoia is still unclear. The King is said to have advised Castlereagh to "consult a physician". On 12 August, Castlereagh committed suicide by cutting his throat with a letter opener.
In a retrospective and therefore necessarily speculative diagnosis, a thoughtful recent study has linked various instances of (at the time) little explained illness to syphilis, possibly contracted at Cambridge: here Stewart's undergraduate studies were interrupted by a mysterious illness first apparent during the closing months of 1787, and which kept him away from Cambridge through the summer of 1788. Later, there were unexplained illnesses in 1801 and 1807, the first described by a contemporary as 'brain fever' which would be consistent with syphilitic meningitis. In addition to the events surrounding the suicide itself, towards the end of his life there are increasing reports of exceptionally powerful rages and sudden bouts of uncharacteristic forgetfulness.
An inquest concluded that the act had been committed whilst insane, avoiding the harsh strictures of the felo de se verdict that would have seen the suicide victim buried with a stake in his heart at a crossroads - an action that last occurred in 1823 before the law was amended in the same year.
His funeral on 20 August was greeted with jeering and insults along the processional route, although not to the level of unanimity projected in the radical press. Lord Londonderry was buried in the Abbey in the shadow of his mentor, William Pitt the Younger. A funeral monument was not erected until 1850 by his half-brother and successor, the 3rd Marquess of Londonderry.
