The First World War was both a European civil war and a clash of global empires. Its impact stretched from the muddy battlefields of Belgium and France to the deserts of modern-day Iraq.

British perceptions of the war are dominated by the Western Front. Soldiers and civilians regarded it at the time as the decisive theatre of military operations. It was likewise the central component of Allied memorialisation of the war after 1918. This was hardly surprising. The number of British dead and wounded in northern France and Belgium - just over two million between 1914 and 1918 - dwarfed the number of British casualties on any other military front.

Both the Allies and the Central Powers tried various means to overcome the stalemate of trench warfare that characterised the fighting on the Western Front from the autumn of 1914 onwards. In April 1915, for example, German forces at the 2nd Battle of Ypres released 168 tons of poisonous chlorine gas against French and Canadian troops. But this dangerous new weapon did not have the intended decisive impact. Within days, Kitchener had secured Cabinet agreement for Britain to respond in kind.

In 1916, while German forces unsuccessfully laid siege to the French fortress of Verdun (February-August), the British launched a major set-piece offensive of their own. The Battle of the Somme began on 1 July 1916 and lasted until 17 November. Nearly 20,000 British officers and men were killed on the first day of fighting - more than on any other day during the war or on any day in any other conflict. Yet, during the five-month offensive, Allied troops made only small territorial gains.

The majority of the British forces on the Western Front came from Britain itself, but there were also large numbers of Indian combat troops as well as soldiers from the Dominions (Canada, Australia, New Zealand and South Africa). Black soldiers from the Caribbean and parts of Africa worked as labourers, often under fire.

However, as on many occasions before, the German army failed to drive home its advantage, and in July, the tide began to turn rapidly. A concerted Allied counter-offensive drove the Germans back beyond the starting point of their March offensive. German military morale crumbled - particularly after the army's 'black day' at the Battle of Amiens on 8 August, when almost 28,000 men were either killed or captured. Within two months, Allied troops had decisively broken through Germany's defensive shield on the Western Front, the Hindenburg Line. Fighting continued until early November, but the war in the West had finally been decided in the Allies' favour.