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

Robert Banks Jenkinson, 2nd Earl of Liverpool, (7 June 1770 – 4 December 1828) was a British statesman and Prime Minister (1812–27). As Prime Minister, Liverpool called for repressive measures at domestic level to maintain order after the Peterloo Massacre of 1819. He dealt smoothly with the Prince Regent when King George III was incapacitated. He also steered the country through the period of radicalism and unrest that followed the Napoleonic Wars. He favoured commercial and manufacturing interests as well as the landed interest. He sought a compromise of the heated issue of Catholic emancipation. The revival of the economy strengthened his political position. By the 1820s he was the leader of a reform faction of "Liberal Tories" who lowered the tariff, abolished the death penalty for many offences, and reformed the criminal law.

The War of 1812 was a conflict fought between the United States and the United Kingdom, and their respective allies from June 1812 to February 1815. Historians in Britain often see it as a minor theater of the Napoleonic Wars; in the United States and Canada, it is seen as a war in its own right.

Peace negotiations began in August 1814, and the Treaty of Ghent was signed on December 24. News of the peace did not reach America for some time. Unaware of the treaty, British forces invaded Louisiana and were defeated at the Battle of New Orleans in January 1815. These late victories were viewed by Americans as having restored national honour, leading to the collapse of anti-war sentiment and the beginning of the Era of Good Feelings, a period of national unity. News of the treaty arrived shortly thereafter, halting military operations. The treaty was unanimously ratified by the US Senate on February 17, 1815, ending the war with no boundary changes.

The Corn Laws were tariffs and trade restrictions on imported food and grain ("corn") enforced in Great Britain between 1815 and 1846. They were designed to keep grain prices high to favour domestic producers and imposed steep import duties, making it too expensive to import grain from abroad, even when food supplies were short.

The laws became the focus of opposition from urban groups who had far less political power than rural Britain. The Irish famine of 1845–1852 forced a resolution because of the urgent need for new food supplies. Prime Minister Sir Robert Peel, a Conservative, achieved repeal with the support of the Whigs in Parliament, overcoming the opposition of most of his own party.

The Second Barbary War (1815) was fought between the United States and the North African Barbary Coast states of Tripoli, Tunis, and Ottoman Algeria. The war ended when the United States Senate ratified Commodore Stephen Decatur’s Algerian treaty on December 5, 1815. However, Dey Omar Agha of Algeria repudiated the US treaty, refused to accept the terms of peace that had been ratified by the Congress of Vienna, and threatened the lives of all Christian inhabitants of Algiers. William Shaler was the US commissioner in Algiers who had negotiated alongside Decatur, but he had to flee aboard British vessels and watch rockets and cannon shot fly over his house "like hail" during the Bombardment of Algiers (1816). He negotiated a new treaty in 1816 which was not ratified by the Senate until February 11, 1822 because of an oversight.

The Battle of Waterloo was fought near Waterloo in present-day Belgium. A French army under the command of Emperor Napoleon Bonaparte was defeated by two of the armies of the Seventh Coalition: a British-led Allied army under the command of the Duke of Wellington, and a Prussian army under the command of Gebhard Leberecht von Blücher, Prince of Wahlstatt. The battle marked the end of the Napoleonic Wars

Augusta Ada King, Countess of Lovelace (née Byron) was an English mathematician and writer, known for her work on Charles Babbage's mechanical general-purpose computer, the Analytical Engine. She was the first to recognise that the machine had applications beyond pure calculation, and published the first algorithm intended to be carried out by such a machine. As a result, she is sometimes regarded as the first to recognise the full potential of a "computing machine" and the first computer programmer.

Lovelace was the only legitimate child of the poet Lord Byron and his wife Anne Isabella "Annabella" Milbanke, Lady Wentworth. Ada translated an article by Italian military engineer Luigi Menabrea, on the Babbage engine, supplementing it with a set of notes, which contain what many consider to be the first computer program, an algorithm designed to be carried out on the engine, if it had ever been built.