He entered Parliament in 1756 as MP for Boroughbridge, but was elevated to the House of Lords a year later after inheriting the title of Duke of Grafton from his grandfather. In 1766 he was appointed First Lord of the Treasury by William Pitt the Elder, and then became the effective leader of the government in 1768 after Pitt resigned due to illness.
Among the first issues he was faced with as Prime Minister was the crisis produced by the French invasion of Corsica. Although initially reluctant to intervene after the trauma of the recently-ended Seven Years War, public opinion and the unexpected success of the Corsicans at the Battle of Borgo eventually encouraged him to take a harder line against France. By January 1769, faced by the threat of war from Britain, France had withdrawn from Corsica and recognised the independence of the island.
Pitt's government had brought the Seven Years War to a successful conclusion, but at tremendous expense. Although Great Britain had succeeded in securing many former French territories in the peace negotiations, including the Canadas, French India and much of the West Indies, it was still forced to try and recoup some of its losses by raising taxes for the general populace.
This particularly angered the colonists in North America, who had long chafed over the fact that they did not have any direct representation in Parliament. In 1770 the Grafton ministry eased taxes in an attempt to quell discontent, but this only encouraged the radicals in Boston and elsewhere. The year 1770 is often quoted as the beginning of the New England Crisis.
In 1773 rioters led by Samuel Adams and the Sons of Liberty boarded and destroyed three ships containing tea in what came to be known as the Boston Tea Party. The public both in Britain and the colonies was outraged, but despite intense domestic pressure Grafton resisted punishing Boston itself too harshly. Only when the colonial assembly refused to arrest Adams or to compensate the government for the tea were the so-called "Intolerable Acts" passed, which were repealed in 1775 when the moderate faction in Massachusetts reached out for reconciliation following the Continental Congress.
The First Continental Congress took place in September 1774 with delegates from twelve colonies and was intended to decide upon a united response to the British measures. The radical faction, including Samuel Adams, John Adams, Patrick Henry and Roger Sherman, favoured a boycott of British imports or even independence. Most delegates, however, had little sympathy for such extreme measures and blamed Massachusetts for its own troubles for refusing to agree to what seemed like a reasonable compromise. Eventually it was decided to send a petition to the King, asking him to respect their rights as Englishmen, and to assemble a Second Continental Congress a year later if no favourable response was received.
Grafton, who had been following the events in America closely, received the petition as soon as it arrived in London. As it happens he was sympathetic to many of the colonist's grievances, and after the Christmas break he, along with Benjamin Franklin, presented the petition to the King and to Parliament.
Franklin was sent back to Philadelphia with the following proposals:
- The Intolerable Acts were repealed, with the exception of the Boston Port Act. The latter act was amended so that it would cease to take effect the moment the perpetrators of the Boston Tea Party were brought to justice.
- Crown officials and military officers were to be made directly subordinate to the provincial legislatures, rather than the Westminster parliament, unless otherwise empowered by means of letters patent.
- Each individual colony was to be entitled to send two Members of Parliament to Westminster.
- A Supreme Court was to be established in each colony for the trying of crimes committed within the bounds of the colony, subordinate only to the King-in-Parliament.
- No further taxes were to be levied specifically on the colonies without the approval of their legislatures.
By the time Franklin returned armed uprisings had already begun in Massachusetts, but most other colonies were biding their time to see what the King had to say. At the Second Continental Congress in summer 1775 a majority of the delegates voted to accept the compromise and to return to being loyal subjects of the Crown.
Nevertheless, the politicians of Massachusetts, Rhode Island and Connecticut disagreed, and those of Virginia were divided. Before long the legislatures of the former three colonies had rejected compromise and declared independence, while a civil war had broken out in Virginia. Prime Minister Grafton appealed to the loyal colonies for assistance in suppressing the rebellion, and many agreed.
By 1778 the rebellions had been crushed. Samuel Adams and Patrick Henry were captured and executed for treason, while several other leaders were deported to the West Indies. Without the agitation encouraged by the radicals, the rebellious colonies slowly returned to the fold.
The Duke of Grafton resigned from the premiership in 1782 due to ill health. He was replaced by his fellow Whig, the Marquess of Rockingham.