Fitzwilliam, William Wentworth (1748–1833), 2nd Earl Fitzwilliam (GB), 4th Earl Fitzwilliam (Ire.), lord lieutenant of Ireland, was born William Fitzwilliam at Milton House, Peterborough, on 30 May 1748, the eldest son of William Fitzwilliam (1720–56), 1st and 3rd Earl Fitzwilliam, and Anne Fitzwilliam (née Watson-Wentworth; d. 1769), daughter of Thomas Watson-Wentworth, 1st marquess of Rockingham (1693–1750). Known as Viscount Milton until he succeeded his father in 1756, he was educated at Eton College (1756–64), following which he went on the grand tour. On his return to England in 1769, he took his seat in the house of lords, and on 10 July 1770 married Lady Charlotte Ponsonby (1747–1822), the daughter of William Ponsonby, 2nd earl of Bessborough (qv).
By the death of his revered maternal uncle, Charles Watson-Wentworth, 2nd marquess of Rockingham, in 1782, Fitzwilliam inherited extensive estates in Yorkshire, Northamptonshire, and Co. Wicklow, which catapulted him to the forefront of the landowning elite in Great Britain. Fitzwilliam provided tangible evidence of the high esteem in which he held his uncle by later adding Wentworth to his name. The inheritance involved considerable responsibilities, the most challenging of which was the expectation, widely shared within whig ranks, that he would assume his uncle's mantle of leadership. Fitzwilliam was more capable in this respect though less experienced than William Cavendish-Bentinck, duke of Portland (qv), but he declined the Irish viceroyalty in 1783 and played only a tangential role in the coalition government named after its unlikely principals, Charles James Fox and Lord North. This did not mean that he found the controversial dismissal of the coalition by George III any easier to accept than other whigs; the deep reverberations from the incident served to confirm him in his conviction that principle as well as propriety required that the ministry headed by William Pitt, which assumed the reins of power in December 1783, was soon replaced by a whig ministry led by his long-time friend, Charles James Fox. To this end, Fitzwilliam played an active part in the house of lords in resisting Pitt's attempt in 1785 to bind Britain and Ireland in a free-trade zone, and he was active once more in 1788–9 when the unexpected illness of George III presented the whigs with an opportunity to create an unlimited regency headed by George, prince of Wales, which, it was widely assumed, would ease their way to power.
Had this come to pass, Fitzwilliam would probably have become first lord of the admiralty, which was not a prospect he relished. Instead, the outbreak of the French revolution posed him and other whigs a still more serious dilemma as to how far they wished to press their commitment to political reform. For whigs like Fitzwilliam, who believed implicitly in deference and in the virtues of an orderly society headed by a monarchy, moderate reform was a logical necessity. However, as the French revolution took a radical, anti-monarchical turn and its British and Irish admirers embraced its radical republican vision, Fitzwilliam became increasingly uneasy, and the outbreak of war between Britain and France in February 1793 encouraged him and most moderate whigs to break with their former friends and allies, led by Fox and Charles Grey. Fitzwilliam was more resistant than the duke of Portland to the suggestion that the whigs should join with Pitt in government, but he was finally won over by the persistent Portland in July 1794.
Fitzwilliam's reward for joining in coalition with Pitt was a seat at the cabinet table and the office of lord lieutenant of Ireland. As a major landowner in that country and a strong believer in the wisdom of redressing legitimate grievances in order to defeat the threat of radicalism and to sustain social and political order, he was convinced of the prudence of pursuing a reformist programme in Ireland. The problem he faced was that a majority of his cabinet colleagues, Pitt and Portland included, and all of those in positions of influence in Ireland, were of the opinion that this was precisely the wrong time to alter the foundations of government in Ireland, and believed that every suggestion that catholics should be admitted to sit in the Irish parliament must be resisted at all costs. Fitzwilliam was present at the cabinet meeting in November when it was determined that the system of government in place in Ireland should remain as it was, but whereas this was accepted by his colleagues, his dislike of Pitt dovetailed with his receptivity to the lobbying of such Irish whigs as Henry Grattan (qv) and George Ponsonby (qv) to incline him to believe that a more reform-minded policy was required if Ireland was not to descend into violent disorder. He was affirmed in this conviction, moreover, by the strength of the demand for reform that he encountered on his arrival in Dublin in January 1795. Fitzwilliam may not have appreciated the extent to which this was inspired by Grattan – who shared his view that reform was essential if the appeal of the example of revolutionary France was to be diminished – and fomented by the leadership of the Catholic Committee, who looked to him for their ‘emancipation’.
Convinced at any event that he must replace the conservative office-holders who dominated the Irish administration with whigs of a more reformist outlook, Fitzwilliam oversaw the replacement of the attorney general Arthur Wolfe (qv) by George Ponsonby. John Beresford (qv), the powerful first commissioner of the revenue, was dismissed and the influential under-secretaries in the civil and military departments, Edward Cooke (qv) and Sackville Hamilton (qv), were also dispensed with. The removal of such experienced office-holders was inherently controversial, but the controversy was magnified in this instance by Fitzwilliam's neglect of the instructions he had received from Pitt not to place his confidence in the Ponsonbys. Moreover, worse was to follow, as Henry Grattan, who had declined an offer of office in the administration, pressed ahead with the preparation of legislation to admit catholics to parliament. Grattan was a difficult man to dissuade once he had determined on a course of action, but Fitzwilliam compounded the problem in various ways. He failed to buy some time by masking his own support for Grattan's measure, and did not make sufficient effort to persuade his ministerial colleagues of its wisdom; it might have been beyond his capacities to bring about agreement to Grattan's legislation, but by declining to convey draft copies of what Grattan had in mind and by not waiting for explicit authorisation before any attempt was made to present the bill, Fitzwilliam contravened both the instructions he had been given before his departure for Ireland and the principle of collective cabinet responsibility. Thus when, on 12 February 1795, Grattan presented the house of commons with a bill for the relief of catholics, Fitzwilliam's days in office were numbered. His recall was set in train within ten days and he departed Ireland to an extraordinarily emotional farewell on 25 March.
This was not the end of the matter. Fitzwilliam felt betrayed by his colleagues, and having failed to secure the establishment of a committee of inquiry into his dismissal in the house of lords, he published a defence of his conduct in the form of letters to the earl of Carlisle; this precipitated a duel with John Beresford at Paddington, near London, on 28 June, though no shots were fired. Thereafter Fitzwilliam opted to revert to a more low-profile public role; he remained firmly within the whig fold, and served during the brief ‘ministry of all the talents' in 1806–7 as lord president of the council. He was by then reconciled with Fox, but not with the duke of Portland, whose reflexive conservatism he found ideologically antipathetic and inconsistent with the whig convictions by which he defined his political principles, and which shaped his life in and out of politics.
Following the death of his wife, Charlotte, in May 1822, Fitzwilliam married, in July 1823, Louisa Ponsonby (née Molesworth; 1749–1824), the daughter of Richard, 3rd Viscount Molesworth, and the widow of William, Baron Ponsonby. Fitzwilliam survived her by nine years, dying at Milton House on 8 February 1833. He was succeeded by his son from his first marriage, Charles William Wentworth Fitzwilliam.