The events of July and August 1914 unfolded in a certain way, but underlying security interests and political attitudes determined the decisions Britain would make.

By Professor William Philpott

Already aligned with one of the alliances that would go to war in 1914, Britain was obliged to take a diplomatic stance during the July crisis. However, while urging a diplomatic settlement to the crisis, British security interests could not be ignored.

Leading Liberal Party politicians, notably Foreign Secretary Sir Edward Grey, argued strongly once hostilities commenced on 31 July that Britain had to support her Entente partners Russia and France or risk diplomatic isolation. More pacifist Liberal politicians dissented. The Unionist Party offered support for Edward Grey’s stance and both navy and army were ready to act in the event of hostilities, having concerted plans with France before 1914.

Although Britain had no formal alliance which required her to enter the war if France was attacked, French and British security interests in north-west Europe were intertwined. It was ‘against British interests that France should be wiped out as a Great Power’, the Prime Minister Herbert Asquith wrote on 2 August. For Britain a balance of power in Europe had long guaranteed the empire’s global security.

On that day, before the German violation of Belgium was evident, the Cabinet guaranteed French maritime security under the terms of their 1912 naval agreement that had been signed after the last crisis with Germany, thereby effectively undertaking to exclude the German fleet from the North Sea and English Channel.

Preventing a hostile power controlling Belgium was a long-standing axiom of British security which Germany’s invasion of Belgium directly challenged. Honouring a long-existing treaty guarantee to preserve Belgian neutrality and answering a small power’s call for assistance, was an honourable way to take the country and empire into the war united. But since this was a collective guarantee that Germany had violated, Britain could justifiably have not intervened for this reason had not her international alignments and the direct German threat to British national security already drawn her in.

An ultimatum sent to Germany not to invade Belgium expired at midnight on 4 August when German troops were already in that country. Britain declared war and mobilised army reservists on 5 August; the navy was already at battle stations.

It is sometimes suggested that it was wrong for Britain to enter the First World War. The political and strategic reasons for declaring war on Germany were valid and logical in 1914, although such calculated realpolitik seems outdated.

Britain’s entry into the war on the side of France and Russia was inevitable at some point. Germany’s violation of Belgium provided the moral pretext for action as well as the practical security concern that obliged it. But even without this reason, Britain could not have stayed out for long without risking, according to Edward Grey, having ‘everyone against us which would be a still greater weakness’, whatever the outcome of the war on the continent.

William Philpott is Professor of the History of Warfare in the Department of War Studies, King’s College London. He is specialist in the history of the First World War and of Anglo-French relations. He is the author of Attrition: Fighting the First World War  and Bloody Victory: The Sacrifice on the Somme.