Outside Britain and its empire, the First World War also ushered in a period of uncertainty and change. Empires fell, to be replaced by republics based on nationalist principles of self-determination. Monarchs fled into exile. People everywhere experienced new rulers and new hardships.

The legacy of the First World War, though positive in some respects, was ultimately a dangerous one. Many of the bitter and unresolved grievances that it aroused cast a long shadow over inter-war Europe.

None of Britain's major allies in 1918 - France, Italy and the USA - emerged in glorious triumph from the war. In economic terms, the conflict had propelled the USA towards global supremacy. However, neither American financial and military power nor the Wilsonian idealism behind the League of Nations persuaded American politicians to adopt a less isolationist foreign policy after 1918.

On 19 November 1919, the US Senate voted to reject the Treaty of Versailles and to refuse membership of the League of Nations. Without American support, the establishment of a viable international system of collective security was stillborn.

Both France and Italy made substantial territorial gains in the post-war settlements: the French, for example, in Alsace-Lorraine, Lebanon and Syria; the Italians in South Tyrol, Istria and parts of Dalmatia. Yet neither country was satisfied.

France's desire to permanently emasculate Germany was compromised by its failure to secure control over such key areas as the Rhineland and the Saarland. The Italian prime minister Vittorio Orlando - who, like his French counterpart Georges Clemenceau, failed to ensure that all of his country's wartime territorial demands were met in Paris - returned home in 1919 to accusations that he had signed 'a mutilated peace'. In France, such frustrated nationalist sentiments were kept in check by an unstable but durable system of parliamentary democracy. In Italy, they formed the popular basis of Benito Mussolini's Fascist dictatorship.

For the defeated Central Powers, the end of the war brought collapse and revolution. The Habsburg empire imploded. Three new states emerged even before the Paris peace conference - Czechoslovakia, Poland and 'the Kingdom of the Serbs, Croats and Slovenes' (known as Yugoslavia after 1929). Austria and Hungary became separate entities, with the former epicentre of the Habsburg empire reduced to a rump state of just eight million people and the last Habsburg emperor, Karl I, forced into exile in Switzerland.

New political forces - most notably nationalism and, for a short time in Hungary under the dictatorship of Béla Kun, Communism - now came to the fore in the region.

Despite substantial losses, both the Ottoman and the German empires survived with their core territories intact. Under the leadership of the war hero Mustafa Kemal, the new republic of Turkey quickly reclaimed some of the territory that it had lost in the Treaty of Sèvres, re-occupying newly independent Armenia in September 1920 and taking back Smyrna from Greece in August 1922.

The new German republic found it harder to come to terms with its reduced status. Saddled with a detested peace treaty and severe economic problems, successive Weimar governments were threatened from the left and the right by violence and revolution: the abortive Spartacist uprising in Berlin in January 1919; the unsuccessful Kapp putsch in March 1920; and the Nazi Party's infamous 'beer hall putsch' in Munich three years later. Although it survived these early attempts to destroy it, the Weimar republic never shook off the stigma of its tarnished origins.

In Russia, the Bolshevik revolution triggered a violent civil war between 'Reds' and 'Whites' that lasted until 1922. More Russians died in this conflict - not only in combat, but also as a result of terror, famine and disease - than in the Great War.

Fearful of a Communist tide sweeping westwards over Europe, many countries, including Britain, offered military assistance to the anti-Bolshevik forces. However, given the costs and dangers of a prolonged campaign in the East, the Allies agreed to withdraw their troops from Russia towards the end of the Paris peace conference. The path was left open for the eventual triumph of the Bolsheviks and the subsequent establishment of the Soviet Union as a fixed part of the international community.

The aftermath of the First World War had a number of themes common to the countries that had fought in it: the decline of monarchism and the concomitant rise of republicanism; the emergence of new 'nation states'; the growth of unemployment, inflation and general economic instability; and the continued use of violence to resolve political disputes.

In too many places, 'peace' still meant conflict by other means. The 'European civil war' did not end in November 1918.