Great Britain
After the defeat of Napoleon in 1815, the Congress of Vienna redrew the map of Europe. One of the new countries thus created was Belgium. Belgium was to be a neutral country, its neutrality "guaranteed" by other countries - who would fight against Belgium if she invaded another country or alongside her if she was herself invaded. One of those guarantors was Great Britain, so when German troops crossed the Belgian border in 1914, Britain found herself at war with Germany and, by extension, Germany's allies.
Of course, the neutrality of Belgium may have been the occasion of Britain's entering the war, but it can hardly be argued as the root cause. The British and German peoples, bosom friends in Napoleon's time, had been slowly drifting apart since the end of the 19th Century. German unification in 1871 had created a new continental power, but during the 1880s and 1890s, Germany began clamouring for colonies abroad, and for a navy to rival that of Britain.
An arms race developed, and by 1912, many - in Britain and Germany - were convinced that a war was inevitable. Most even hoped for it. The Germans wanted to take their rightful place on the world stage, while the British sought to silence the upstart nation and maintain their own predominance.
King George V
Once war had been declared in 1914, the British Expeditionary Force landed in France. While the French threw men against the German positions in Alsace-Lorraine, the Germans advanced through Belgium. The French army advanced to meet them, the BEF on the left of the line. The French were defeated, but the rearguard action of the BEF at Mons (23 August) prevented the defeat from becoming a rout. The BEF withdrew in line with the French, fighting a series of rearguard engagements until 27 August, when the British II Corps made a stand at Le Cateau and held the Germans off.
The BEF was a small (100,000), professional army. The German Kaiser is said to have referred to them as a "contemptible little army" and the BEF - with typical British humour - took it to heart and referred to themselves as the "Old Contemptibles".
With the Germans checked at the Marne, the two armies tried desperately to turn each others' flanks in a period that has become known as the "Race to the Sea" because it ended with the lines drawn across half of Europe, from the border with neutral Switzerland to the Belgian coast east of Ypres.
British stretcher bearers at Passchendaele, 1917
The four-year stalemate of the Western Front is perhaps the best known image of the Great War, and it was in Belgium that the British army was stationed, between the French and the Belgians (the remnants of whose army occupied the coastal zone). Names like Ypres, Passchendaele and the Somme conjure up for most people the quintessence of World War One.
However, the British experience of 1914-18 wasn't limited to the mud and wire of Flanders. The Royal Navy proceeded to sea, its mission to sweep the seas clear of the enemy. German colonies in Africa, China and the pacific were the first targets. The German pacific islands fell quickly, but the German naval forces in the region were tougher nuts to crack. The German admiral, von Spee, sank two British cruisers at Coronel before his raid on the Falklands backfired, resulting in the destruction of his task force.
Royal Marines disembark in Ostende
1915 was the year in which the war widened from the Western Front as far as Britain was concerned. The German fleet mounted a raid in the North Sea, but the Royal navy had been warned by radio intercepts and sank Blucher at Dogger Bank. The Germans retreated from the high seas and began to rely on a submarine campaign. Not until 1916 would the German fleet be brought to battle, at Jutland. The day ended indecisively, but the German High Seas Fleet never again ventured out of port.
Meanwhile, the Royal Navy supported the landings at Gallipoli. Gallipoli was a disastrous campaign for the allies. Although usually thought of as an Australian and New Zealand campaign, British troops fought on the Gallipoli peninsula for the period of the campaign.
The same year, British troops landed at Salonika as part of an Anglo-French expeditionary force, originally intended to support Greece against their Bulgarian neighbours.
The Middle East, meanwhile, saw the initiation of hostilities between Britain and Turkey on two further fronts. Allenby's Egyptian Expeditionary Force attacked up the coast of Palestine towards Jerusalem, while Nixon's Mesopotamian expedition (including many Indian troops) established a bridgehead at Basra and advanced on Baghdad. Both were aided by the renowned Col. T E Lawrence and his Arabian army.
British troops at Gaza
In all, the British Empire is reckoned to have lost some 888,000 men in battle during World War One. The figure scarcely even begins to hint at the effect that the war had on the nation. Although victorious, Britain entered the 1920s as an exhausted, financially ruined country, with almost an entire generation of young men wiped out.