Portland was known before 1762 by thecourtesy title Marquess of Titchfield. He held a title for every degree of British nobility: duke, marquess, earl (Earl of Portland), viscount (Viscount Woodstock), and baron (Baron Cirencester). He was the leader of the Portland Whigs faction, which broke with theWhig leadership ofCharles James Fox and joined withWilliam Pitt the Younger in the wake of theFrench Revolution.
In December 1757, the nineteen-year-old Lord Titchfield was sent to study underLord Stormont for a year inWarsaw, accompanied by Stormont's secretary,Benjamin Langlois. Stormont was to superintend all expenditures on his equipage, while Langlois was to hire local masters and direct the studies of the teenaged Titchfield. The books he directed him to read were ancient history, modern history and general law.[7]
In 1759, Titchfield travelled with Langlois through Germany to Italy, spent a year inTurin, and then went on toFlorence. When Stormont was appointed ambassador toVienna in 1763, Langlois went with him as Secretary of the embassy.[8]
Portland served asLord Lieutenant of Ireland in Rockingham'ssecond ministry (April–August 1782). He faced strong demands for conciliatory measures following years of coercion and taxation brought about by the British government's engagement in theAmerican Revolutionary War.[13] Portland resolved to make concessions and, overcoming the resistance ofLord Shelburne, the Home Secretary to whom he reported, convinced Parliament to repeal theDeclaratory Act and to modifyPoynings' Law.[14] Following Rockingham's death, Portland resigned from Lord Shelburne's ministry along with other supporters ofCharles James Fox.[15]
In April 1783, Portland was selected as the titular head of a coalition government asPrime Minister, whose real leaders were Charles James Fox andLord North. He served asFirst Lord of the Treasury in the ministry until its fall in December that same year. During his tenure, theTreaty of Paris was signed, which formally ended the American Revolutionary War. The government was brought down after it had lost a vote in the House of Lords on its proposed reform of theEast India Company afterGeorge III had let it be known that any peer voting for the measure would be considered his personal enemy.[16]
In 1789, Portland became one of several vice presidents ofLondon'sFoundling Hospital. The charity had become one of the most fashionable of the time, with several notables serving on its board. At its creation, 50 years earlier, Portland's father,William Bentinck, 2nd Duke of Portland, had been one of the founding governors, as listed on the charity'sroyal charter granted byGeorge II. The hospital had a mission to care for the abandoned children in London, and it achieved rapid fame through its poignant mission, its art collection donated from supporting artists and the popular benefit concerts byGeorge Frideric Handel. In 1793, Portland took over the presidency of the charity from Lord North.
Along with many other conservative Whigs such asEdmund Burke, Portland was deeply uncomfortable with theFrench Revolution; he broke with Fox over that issue and joined Pitt's government asSecretary of State for the Home Department in 1794. When the British fleets atSpithead and the Nore mutinied between April and June 1797, Portland sent magistrates to investigate and report on any connections to seditious societies, though none were found.[17] As Home Secretary, Portland oversaw the administration of patronage and financial inducements, which were often secret, to secure the passage of theAct of Union 1800.[18] He continued to serve in the cabinet until Pitt's death in 1806, from 1801 to 1805 asLord President of the Council[5] and then as aMinister without Portfolio.
Portland's second government saw the United Kingdom's complete isolation on the continent but also the beginning of its recovery with the start of thePeninsular War. In late 1809, with Portland's health poor and the ministry rocked by thescandalous duel between Canning and Castlereagh, Portland resigned and died shortly thereafter.
He had lived expensively: with an income of £17,000 a year (worth £577,000 in 2005),[20] he had debts at his death computed at £52,000 (£1.76 million in 2005),[20] which were paid off by his succeeding son by selling off some property, includingBulstrode Park.[21]
ThePortland Vase of Roman glass was given its name because it was owned by Portland at his family residence at Bulstrode Park.
Portland Parish, in Jamaica, was named after him. The Titchfield School, founded in 1786, is in the parish and is also named in his honour. The school's crest is derived from his personal crest.
Portland Bay in Victoria, Australia was named in 1800 by the British navigatorJames Grant. The city ofPortland is located on the bay.
The department ofManuscripts and Special Collections, The University of Nottingham holds a number of papers relating to him. His personal and political papers (Pw F) are part of the Portland (Welbeck) Collection, and the Portland (London) Collection (Pl) contains his correspondence and official papers, especially in series Pl C.
The Portland Estate Papers held at Nottinghamshire Archives also contain items relating to the 3rd Duke's properties.
The Portland Collection[22] of fine and decorative art includes pieces owned and commissioned by him, including paintings by George Stubbs.
Out of a ducal coronet proper two arms counter-embowed vested Gules, on the hands gloves Or, each holding an ostrich feather Argent (Bentinck); A snake nowed proper (Cavendish)
Escutcheon
Quarterly: 1st and 4th,Azure a cross moline Argent (Bentinck); 2nd and 3rd,Sable three stags' heads cabossed Argent attired Or, a crescent for difference (Cavendish)
Supporters
Two lions double queued, the dexter Or and the sinister sable
^The Register of Births and Baptisms in the Parish of St James within the Liberty of Westminster. 1761-1786. 13 April 1778.
^The Register of Births and Baptisms in the Parish of St James within the Liberty of Westminster. 1761-1786. 17 June 1780.
^Wilkinson, David (2003).The Duke of Portland – Politics and Party in the Age of George III. Basingstoke, UK / New York City: Palgrave Macmillan. pp. 35–38.ISBN978-0333963852.
^Easton, Callum (2025).The 1797 Naval Mutinies and Popular Protest in Britain: Negotiation through Collective Action. Palgrave MacMillan. pp. 30–31, 190, 272.ISBN978-3-031-98839-4.