General John Churchill, 1st Duke of Marlborough, 1st Prince of Mindelheim, 1st Count of Nellenburg, Prince of the Holy Roman Empire, KG PC (//, often /-/; 26 May 1650 – 16 June 1722 O.S.[a]) was an English soldier and statesman whose career spanned the reigns of five monarchs. From a noble family, he served first as a page at the court of the House of Stuart under James, Duke of York, through the 1670s and early 1680s, earning military and political advancement through his courage and diplomatic skill.
Churchill's role in defeating the Monmouth Rebellion in 1685 helped secure James on the throne, yet just three years later he abandoned his Catholic patron for the Protestant Dutchman, William of Orange. Honoured for his services at William's coronation with the earldom of Marlborough, he served with further distinction in the early years of the Nine Years' War, but persistent charges of Jacobitism brought about his fall from office and temporary imprisonment in the Tower. It was not until the accession of Queen Anne in 1702 that Marlborough reached the zenith of his powers and secured his fame and fortune.
His marriage to the hot-tempered Sarah Jennings – Anne's intimate friend – ensured Marlborough's rise, first to the Captain-Generalcy of British forces, then to a dukedom. Becoming de facto leader of Allied forces during the War of the Spanish Succession, his victories on the fields of Blenheim (1704), Ramillies (1706), Oudenarde (1708), and Malplaquet (1709), ensured his place in history as one of Europe's great generals. But his wife's stormy relationship with the Queen, and her subsequent dismissal from court, was central to his own fall. Incurring Anne's disfavour, and caught between Tory and Whig factions, Marlborough, who had brought glory and success to Anne's reign, was forced from office and went into self-imposed exile. He returned to England and to influence under the House of Hanover with the accession of George I to the British throne in 1714.
Marlborough's insatiable ambition made him the richest of all Anne's subjects. His family connections wove him into the fabric of European politics (his sister Arabella became James II's mistress, and their son, the Duke of Berwick, emerged as one of Louis XIV's greatest Marshals). His leadership of the allied armies consolidated Britain's emergence as a front-rank power. He successfully maintained unity among the allies, thereby demonstrating his diplomatic skills. Throughout ten consecutive campaigns during the Spanish Succession war, Marlborough held together a discordant coalition through his sheer force of personality and raised the standing of British arms to a level not known since the Middle Ages. Although in the end he could not compel total capitulation from his enemies, his victories allowed Britain to rise from a minor to a major power, ensuring the country's growing prosperity throughout the 18th century.