George III was the third British monarch of the House of Hanover, but unlike his two predecessors, he was born in Great Britain, spoke English as his first language, and never visited Hanover. His reign was marked by a series of military conflicts involving his kingdoms, much of the rest of Europe, and places farther afield. Early in his reign, Great Britain defeated France in the Seven Years' War, becoming the dominant European power in North America and India. However, many of Britain's American colonies were soon lost in the American War of Independence. Further wars against revolutionary and Napoleonic France from 1793 concluded in the defeat of Napoleon at the Battle of Waterloo in 1815.

Later in life, George III had recurrent mental illness. After a final relapse in 1810, a regency was established, and George III's eldest son, George, Prince of Wales, ruled as Prince Regent.

The Napoleonic Wars were a series of major conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European powers formed into various coalitions, financed and usually led by the United Kingdom. The wars stemmed from the unresolved disputes associated with the French Revolution and its resultant conflict

William Wyndham Grenville, 1st Baron Grenville, (25 October 1759 – 12 January 1834) was a British Pittite Tory and politician who served as Prime Minister of the United Kingdom from 1806 to 1807, though he was a supporter of the British Whig Party for the duration of the Napoleonic Wars.

Following Pitt's death in 1806, Grenville became the head of the "Ministry of All the Talents", a coalition between Grenville's supporters, the Foxite Whigs, and the supporters of former Prime Minister Lord Sidmouth, with Grenville as First Lord of the Treasury and Fox as Foreign Secretary as joint leaders. The Ministry ultimately accomplished little, failing either to make peace with France or to accomplish Catholic emancipation (the later attempt resulting in the ministry's dismissal in March, 1807). It did have one significant achievement, however, in the abolition of the slave trade in 1807.

William Henry Cavendish Cavendish-Bentinck, 3rd Duke of Portland, (14 April 1738 – 30 October 1809) was a British Whig and Tory politician during the late Georgian era. He served twice as British prime minister, of Great Britain (1783) and then of the United Kingdom (1807–09). The twenty-four years between his two terms as Prime Minister is the longest gap between terms of office of any British prime minister.

During his tenure the Treaty of Paris was signed formally ending the American Revolutionary War. The government was brought down after losing a vote in the House of Lords on its proposed reform of the East India Company after George III had let it be known that any peer voting for this measure would be considered his personal enemy.