The fierce political battle that preceded Britain's eventual entry into the First World War

There are two reasons for this. First, the Balkans were largely irrelevant to British interests. Secondly, British politicians were preoccupied with the prospect of civil war in Ulster. Apart from Italy, the UK was the last of the great powers to become embroiled in the Great War.

The British Cabinet did not consider the question of military intervention until July 24 – almost a whole month after the assassination at Sarajevo.

Cabinet opinion was divided but the majority opposed military intervention. On July 29 Sir Edward Grey, the foreign secretary, could not even persuade his colleagues to agree to a declaration of support for France.

On August 1 Grey and Winston Churchill, the First Lord of the Admiralty, pressed for mobilisation but Lloyd George, the chancellor of the Exchequer, and others were resolutely opposed.

Despite German intentions becoming increasingly obvious, H H Asquith, the prime minister, noted that that the Cabinet was still split on August 2. It was only the German ultimatum to Belgium – a requirement of the Schlieffen plan by which German armies would advance through Belgium into France, swing west of Paris and then encircle the French capital – on August 3 which tipped the scales in favour of British intervention.

The UK declared war on Germany on August 4. Even so, two Cabinet ministers resigned.

While scrutiny of events leading to the UK’s declaration of war in August 1914 suggests that the British people almost escaped involvement in the Great War, familiarity with the long-established principles which guided British foreign policy would suggest otherwise and that British involvement was inevitable.

For over three centuries British policy had pursued the maintenance of a balance of power which would allow no single nation – whether Philip II’s Spain or Louis XIV and Napoleon’s France – to dominate the continent. Therefore, the UK became involved – not because of ‘gallant little Belgium’ – but because Germany threatened British interests and the European balance of power.

The Foreign Office assumed that if the UK remained aloof and stood aside Germany would have easily defeated France and Russia and have imposed a new hegemony on Europe.

In his memoirs – entitled ‘Twenty-Five Years’ – Grey observed: ‘To stand aside would mean the domination of Germany; the subordination of France and Russia; the isolation of Britain; the hatred of her by both those who had feared and those who had wished for her intervention; and ultimately that Germany would wield the whole power of the continent.’

This view is reiterated throughout Grey’s memoirs. For example, he also wrote: ‘If Britain had stood aside, Germany … would then [have been] supreme over all the Continent of Europe and Asia Minor, for the Turk would be with a victorious Germany.’

In ‘The World Crisis 1911-1918’ Churchill subscribed to the same worldview: Britain ‘could not, for our own safety and independence, allow France to be crushed as the result of aggressive action by Germany’.

John Morley, biographer of Gladstone, upholder of the Gladstonian Liberal conscience and one of the two Cabinet ministers to resign from the government, saw the UK’s role as defending France and subjugating Germany rather than upholding decency and honour in international affairs.

Asquith in his book – entitled ‘The Genesis of War’ – observed: ‘It is impossible for people of our blood and history to stand by … while a big bully sets to work to trash and trample to the ground a victim who has given him no provocation.’

However, Morley’s view is almost certainly closer to the truth than Asquith’s quasi-Wilsonian assertions about protecting freedom and upholding the rights of small nations.

The advantage of making Belgium the cause of the UK’s declaration of war was that intervention on behalf of the neutrality and independence of ‘gallant little Belgium’ looked rather more principled than the realpolitik involved in propping up France in the face of German aggression. A second advantage was that the cause of Belgium rallied British public opinion far more effectively than going to France’s aid ever could have done. Even so, as the resignation of two Cabinet colleagues demonstrates, Grey was overstating the case in claiming: ‘Our coming into the war at once and united was due to the invasion of Belgium.’

Whether one chooses to focus on the immediate events leading to the British declaration of war on Germany or to take the long view, there is validity in asking what would have happened if the UK had stood aside. There can be no serious doubt that the history and experience of the British people in the 20th century would have been radically different and possibly happier too.

British involvement was very costly. British casualties (including those from the Empire) of the war amounted to 908,371 or more than 10% cent of those mobilised. The British death toll was much greater than that of the Second World War.

The financial cost was also immense. In four years the National Debt rose from £650 million to a staggering £7,435 million. The UK started the war as the ‘world’s banker’ and in 1918 ended up owing the United States $5 billion.

If war was waged to prevent German hegemony in Europe, it clearly failed. Within 20 years a new and reinvigorated Germany – Hitler’s Third Reich – posed a far more serious threat to a weaker and impoverished UK, European civilisation and the peace of the world. Was German hegemony in western Europe not inevitable and irresistible?

The war failed ‘to end all wars’ because the Second World War was a direct consequence of the 20th century’s first global conflict. As George Kennan, the American diplomat and historian of Ulster-Scots descent, observed the Great War was ‘the great seminal catastrophe of the 20th century’, sowing the seeds of the Second World War, Communism, Nazism, the Holocaust and the Gulag.