The 20th Century

This section covers the First World War, the partition of Ireland, the inter-war years, and the Second World War — the period that reshaped Britain and its role in the world.

The First World War

The early 20th century was a time of optimism in Britain — a global superpower with a vast Empire, powerful navy and thriving industry. It was also an era of social reform: financial support for the unemployed, old-age pensions, free school meals, workplace safety laws, better town planning, and — for the first time — a salary for MPs, opening public life to more people.

The assassination of Archduke Franz Ferdinand of Austria on 28 June 1914 triggered the First World War, though rising nationalism, militarism, imperialism and a divided Europe had already set the conditions for conflict. Britain fought as part of the Allied Powers (with France, Russia, Japan and later the US, among others) against the Central Powers (mainly Germany, Austria-Hungary and the Ottoman Empire). The whole British Empire was drawn in — over a million Indian troops served, alongside soldiers from the West Indies, Africa, Australia, New Zealand and Canada.

Casualties were immense: more than 2 million British casualties overall, including around 60,000 on the first day of the Battle of the Somme alone in July 1916. The war ended at 11am on 11 November 1918 with Allied victory.

The Partition of Ireland

In 1913 the British government promised "Home Rule" — a self-governing Ireland still part of the UK — but Protestants in the north threatened to resist by force, and the outbreak of war delayed any change. Irish Nationalists launched the Easter Rising in Dublin in 1916; its leaders were executed, and a guerrilla war followed.

A 1921 peace treaty split Ireland in two: the six mainly Protestant counties in the north remained part of the UK as Northern Ireland, while the rest became the Irish Free State, becoming a republic in 1949. Ongoing disagreement over the split led, decades later, to a prolonged period of violence known as "the Troubles."

The Inter-War Period

Living conditions improved through the 1920s, with new public housing built across the country. The 1929 Great Depression then brought mass unemployment to some regions — traditional industries like shipbuilding suffered, while new industries like automobiles and aviation grew. Car ownership doubled between 1930 and 1939. It was also a period of cultural growth, with writers like Graham Greene and Evelyn Waugh, economist John Maynard Keynes, and the BBC beginning radio broadcasts in 1922 and the world's first regular television service in 1936.

The Second World War

Adolf Hitler came to power in Germany in 1933 and began rearming and expanding German territory. When Hitler invaded Poland in 1939, Britain and France declared war. The main Axis powers were Germany, Italy and Japan; the main Allies included the UK, France, Poland and (from 1941) the Soviet Union and the United States.

As France fell in 1940, Winston Churchill became Prime Minister and Britain's wartime leader.

Over 300,000 British and French troops were evacuated from the beaches of Dunkirk in 1940, aided by civilian volunteers in small boats — giving rise to the phrase "the Dunkirk spirit." Britain then won the Battle of Britain that summer, flying Spitfires and Hurricanes to repel the German air force, though London and other cities endured sustained night bombing known as the Blitz — giving rise to the phrase "the Blitz spirit."

The United States entered the war after Japan bombed Pearl Harbor in December 1941. On D-Day, 6 June 1944, Allied forces landed in Normandy, eventually pushing into Germany; the Allies defeated Germany in May 1945. The war against Japan ended in August 1945 after the US dropped atomic bombs on Hiroshima and Nagasaki.

Check That You Understand

• What happened during the First World War
• The partition of Ireland and the establishment of the UK as it is today
• The events of the Second World War