George Montagu, 4th Duke of Manchester, was born on April 6, 1737, the son of Robert Montagu, 3rd Duke of Manchester, and his wife, Harriet Dunch. He began his career in the Huntingdonshire regiment of militia in 1757. On March 28, 1761, he was elected as a Member of Parliament for Huntingdonshire, and in May of 1762, he succeeded to the dukedom upon the death of his father, from whom he also inherited the sinecure of collector of the subsidies of tonnage and poundage outwards in the port of London, worth £1500. On October 23, 1762, Manchester married Elizabeth Dashwood, daughter of Sir James Dashwood, second baronet, of Kirtlington Park, Oxfordshire, and Elizabeth Spencer. They had the following children: George Montagu, Viscount Mandeville (1763--1772); Caroline Maria Montagu (1770-1847); William Montagu, 5th Duke of Manchester (1771-1843); and Frederick Montagu (1774-1827).
From 1763 to 1770, Manchester served as lord of the bedchamber, and after the fall of the Grafton ministry in January, he resigned his position and went into opposition. As the struggle with the colonies intensified, Manchester showed himself a supporter of the Americans. He rose to particular prominence after he spoke in favor of Chatham's bill for a provisional settlement with the colonies on February 1, 1775. He also condemned trade restrictions on New England and preferential treatment for the southern colonies in North America. In the second Rockingham administration in 1782, Manchester was appointed lord chamberlain as well as privy councilor. The next spring, he was named ambassador to France to supervise the conclusion of treaty negotiations between Great Britain and France, Spain, and the Netherlands, but negotiations were too far long for Manchester to win many concessions for the British. Treaties with France and Spain were signed on September 3, 1783, at Versailles. The British treaty with the Netherlands was signed at Paris on May 20, 1784. Manchester died after a brief illness on September 2, 1788.