William Henry Nassau de Zuylestein, 4th Earl of Rochford, KG, PC (17 September 1717 O.S. – 29 September 1781) was a British courtier, diplomat and politician. He occupied senior ambassadorial posts at Madrid and Paris, and served as Secretary of State in both the Northern and Southern Departments. He is credited with the earliest-known introduction of the Lombardy poplar to England in 1754.

He was a personal friend of such major cultural figures as the actor David Garrick, the novelist Laurence Sterne, and the French playwright Beaumarchais. George III valued Rochford as his expert advisor on foreign affairs in the early 1770s, and as a loyal and hard-working cabinet minister. Rochford was the only British secretary of state between 1760 and 1778 who had been a career diplomat.

Rochford played key roles in the Manila Ransom negotiation with Spain (1763–66), the French acquisition of Corsica (1768), the Falkland Islands crisis of 1770–1, the crisis following the Swedish Revolution of 1772, and the aftermath of the Royal Marriages Act 1772. In addition to his work as foreign secretary, he carried a heavy burden of domestic responsibilities in the early 1770s, especially Irish affairs. He was a key member of the North administration in the early phase of the American War of Independence. Illness and a political scandal forced him from office in November 1775.

Early life

William Henry Nassau van Zuylestein was born in 1717, the elder son of Frederick Nassau van Zuylestein, 3rd Earl of Rochford, and his wife Elizabeth ('Bessy') Savage, daughter of the 4th Earl Rivers. His ancestry was Anglo-Dutch, descended in an illegitimate line from William the Silent's son Frederick Henry (1584–1647), Prince of Orange. Rochford's grandfather and great-grandfather both had English wives, ladies-in-waiting at the courts of William II and William III of Orange. His grandfather was a close companion of William III, accompanying him to England in the Glorious Revolution of 1688–9, and later rewarded with the earldom of Rochford.

Educated at Eton College (1725–32) as Viscount Tunbridge, Rochford's school friends included three future secretaries of state, Conway, Halifax and Sandwich. However, he also made a lifelong enemy at Eton of the Prime minister's son, the influential writer Horace Walpole. Instead of going to university, Rochford was sent to the Academy at Geneva, where he lodged with the family of Professor Antoine Maurice. From Geneva he emerged as fluent in French as he was in Dutch and English, and succeeded his father as 4th Earl of Rochford in 1738 at the age of twenty-one.

Courtier Rochford was appointed a Gentleman of the Bedchamber to George II in 1739 (a mark of special royal favour) and served in this role until 1749. He inherited strong Whig principles and was a loyal supporter of the Hanoverian Protestant succession, but also admired Sir Robert Walpole's peaceful foreign policy. At the time of the 1745 Jacobite rebellion he offered to raise a regiment, but this was not needed. He was active in Essex politics in the government's interest, but he was no orator and made no impression in the House of Lords. He was appointed Vice-Admiral of Essex in 1748. Though ambitious for high political office, he avoided the factions and cultivated the King's son, the Duke of Cumberland, as his patron. Cumberland successfully lobbied for Rochford to be given a diplomatic post at the end of the War of the Austrian Succession, and he was named Envoy to Turin in January 1749.

Envoy at Turin

Rochford arrived at Turin on 9 September 1749. This was still the most important of the Italian courts for British foreign policy at this time, and he started as Envoy Extraordinary and Plenipotentiary, the highest rank in the British diplomatic service short of ambassador. However, he had agreed to accept an ordinary Envoy's salary for a probationary period, and this gave him a strong incentive to show zeal and become a thoroughly professional diplomat. His first negotiations, on behalf of a company of English miners and the Protestant Vaudois communities of the Piedmont Alps, were entirely successful, and he then obtained his full salary. He ingratiated himself with King Charles Emmanuel III by accompanying him on early morning hunting rides. Rochford made useful friends at court, and was highly regarded by the diplomatic corps at Turin. He played a minor but useful role in the complex negotiations for the Treaty of Aranjuez (1752). He made a tour of Italy in 1753 and used a spy to gain intelligence of the Young Pretender's court at Rome. He also made full use of British consuls in the region to obtain information about trade matters and French involvement in Corsica, rewarding them with the removal of the duty on British shipping at Villafranca.

Lord Lieutenant of Essex

Recalled from Turin for the duration of the Seven Years' War (1755–63), Rochford resumed his career as a courtier, appointed by George II as First Lord of the Bedchamber and Groom of the Stole, highly prestigious posts. He was also appointed a member of the Privy Council in 1755. As Lord Lieutenant of Essex from May 1756, Rochford was closely involved in forming the Essex regiment of militia, becoming its Colonel in November 1759. At the death of George II in 1760 Rochford lost his lucrative court posts, but was compensated with a generous pension. He spent the early 1760s involved in local Essex politics and 'improved' the Park at his St Osyth estate, adding a formal Dutch garden and a maze. However, his landed income was small for an earl, and a return to diplomacy became a financial necessity. He was named Ambassador to Spain on 18 June 1763.

Ambassador to Spain and France

Rochford's secret instructions for his Madrid embassy were mainly concerned with countering French influence over the king, Carlos III, and reporting on Spain's naval reconstruction after her late and disastrous entry into the Seven Years' War. His first major negotiation resulted from Spain's expulsion of British logwood cutters from the Yucatán Peninsula in Honduras. With strong support from Grenville's administration, Rochford's threats of naval force made the Spanish back down, but gave him a reputation as an anti-Bourbon. Less successful were his efforts to compel Spain to pay the disputed Manila Ransom, which the French foreign minister Étienne François de Choiseul, Duke of Choiseul suggested should be submitted to arbitration. Rochford's alertness uncovered a French plot to set fire to British naval dockyards, a scheme which was postponed until 1770. His friendship with the British consul-general at Madrid, Stanier Porten (uncle of the historian Edward Gibbon) deepened his interest in trade matters, and he used the consuls as well as paid spies to get accurate information about Spain's naval rebuilding. While at Madrid he befriended the young French playwright Beaumarchais, whose experiences in Spain later formed the basis of his play The Marriage of Figaro. Near the close of his embassy, Rochford was an eyewitness to the Esquilache Riots of 1766.

Rochford's appointment to Paris was unexpected, and he left Madrid in such haste that he had to pawn his plate to settle his debts. He insisted on taking the exceptionally capable Porten to Paris as his secretary of embassy. Choiseul at once embroiled Rochford in a scheme to trade off Britain's claim to the Manila ransom for relinquishment of the Falkland Islands, but the misreporting of a previous ambassador, Lord Hertford, and the inexperience of the secretary of state, Lord Shelburne, wrecked this transaction. Choiseul was furious, and unfairly blamed Rochford. Rochford was almost the only member of the diplomatic corps at Paris brave enough to stand up to Choiseul's bullying, and their negotiations over such matters as Dunkirk, the Canada Bills and the East India Company's claim for compensation for wartime expenses in India were often acrimonious. Rochford prepared thoroughly and mastered the details, winning grudging concessions from Choiseul on all three issues.

Choiseul's greatest coup (and Rochford's greatest failure) concerned France's secret acquisition of Corsica from the Republic of Genoa in 1768. Though Rochford gave early warning of the likely terms, and paid a spy to get a copy of the draft treaty, the British cabinet led by Lord Grafton was too preoccupied by rioting in London and failed to support their ambassador in Paris. Rochford also had the misfortune to fall seriously ill for a fortnight at the height of the crisis, enabling Choiseul to clinch the deal with Genoa. Britain's protests thereafter were ineffectual, and an angry Rochford returned to London to resign his embassy. Instead, he was offered a cabinet seat, which he finally accepted on 21 October 1768, on condition that Porten became his under-secretary.

Northern Secretary

Contemporary observers such as Edmund Burke and the anonymous letter-writer Junius thought it odd that Rochford was appointed northern secretary when all of his diplomatic experience had been in southern courts, but Lord Weymouth had insisted on taking the Southern Department as the more important of the secretaryships. British foreign policy, and Britain's reputation in Europe, had sunk to their lowest ebb of the eighteenth century thanks to the 1768 Corsican fiasco, but Rochford's realistic and capable handling of his new portfolio strengthened British foreign policy in several ways. British diplomats abroad were relieved to be dealing with a secretary of state who knew the business of diplomacy, and regularly kept them informed. Hamish Scott has suggested that Rochford 'almost single-handed' averted the impending shipwreck for Britain's reputation in Europe.

Britain's main goal at this time was a treaty of alliance with Russia, but the Empress Catherine II and her foreign minister Panin insisted on a hefty subsidy, which Rochford refused. Instead he persuaded George III to pour secret service money into Swedish politics, to support Russia and undermine French influence. Britain's envoy at Stockholm, Sir John Goodricke, made adroit use of this money, and helped to maintain Sweden's liberal constitution. According to Michael Roberts, Rochford was much more practical and realistic than Choiseul in his handling of Swedish affairs.

Falklands Crisis

Spain's expulsion of a British garrison from the Falkland Islands in May 1770 sparked a major diplomatic crisis that brought Europe to the brink of war. Historians have hitherto attributed the resolution of this crisis to a 'secret promise' by the British Prime Minister Lord North that Britain would quietly evacuate the islands at some future date if the Spanish agreed to disavow their officers and restore the fort to Britain. Recent research in the foreign diplomatic archives suggests an entirely different view of the British side of this crisis. Far from resolving the crisis, North's 'secret promise' nearly wrecked an agreed policy of firm response backed by the threat of naval force. This was Rochford's policy, backed by George III. Though he was Northern Secretary in 1770, Rochford's advice to cabinet as a former ambassador to Madrid and Paris was decisive. Weymouth's laziness and frequent absences left his Southern portfolio for Rochford to manage as well as his own. It was Rochford who ordered the Admiralty to prepare a fleet for war, and sent a simple demand for disavowal and restitution to Madrid. Spain's response crucially depended on French support in the event of war, and France began to prepare a fleet, but the French king's dismissal of Choiseul in December 1770 removed that prospect, and the recall of the British envoy Harris from Madrid showed that Britain was still prepared to go to war. Weymouth also resigned in December 1770, and Rochford replaced him as southern secretary on 19 December 1770.

Southern Secretary