The First World War was the first truly global conflict. From 1914 to 1918, fighting took place across several continents, at sea and - for the first time - in the air. It cost the lives of over ten million soldiers.
In the First World War, the cavalry could no longer deliver the decisive charges it had performed in the past. But it continued to carry out a variety of useful roles that contributed to British success.
Field Marshal Jan Christiaan Smuts successfully led troops against Britain in the Boer War. He later commanded the South African Defence Force fighting alongside British soldiers in several First World War campaigns.
After the Armistice in November 1918, millions of soldiers hoped they would soon go home. But demobilising so many troops was a huge task. How best to mark the Allied victory and commemorate the fallen also became subjects for debate.
On Easter Monday 1916, Irish nationalists launched an armed revolt against British rule in Ireland. Although quickly suppressed by the British Army, the rising was a seminal moment in modern Irish history.
The struggle against the Turks in Egypt and Palestine began with a test of endurance and engineering in harsh desert terrain. It evolved into a fast-moving mobile campaign, which resulted in Allied victory and the fall of the Ottoman Empire.
In 1917, Germany adopted a defensive strategy on the Western Front to counter the growing strength of the Allies. Despite launching several offensives, and suffering heavy casualties, the Allies achieved mixed results.
Throughout the First World War, British Empire soldiers fought a guerrilla campaign against a small German force in East Africa. Led by Colonel Paul von Lettow-Vorbeck, the Germans inflicted many casualties and avoided defeat in the field.
During 1914-18, British troops fought the Turks in Mesopotamia. After many setbacks, they finally took Baghdad in March 1917. This marked the high point of a long and tragic campaign fought in a harsh climate.
In 1918, the British assembled a handpicked unit to carry out a daring secret mission to the Caucasus. Their aim was to unify into an effective force the various anti-Bolshevik and anti-Turkish groups fighting there.