Why did both sides in the war want more allies to join the war?

On 28 June 1914, Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, and his wife were assassinated by a Serbian-backed terrorist. During the crisis that followed, Europe's leaders made a series of political, diplomatic and military decisions that would turn a localised conflict in south-east Europe into a global war.

Austria-Hungary, with German encouragement, declared war on Serbia on 28 July. Russia's support of Serbia brought France into the conflict. Germany declared war on Russia on 1 August and France on 3 August. Germany's violation of Belgian neutrality and British fears of German domination in Europe brought Britain and its empire into the war on 4 August.

These actions reflect the fears, anxieties and ambitions of the European powers. The decisions for war were made in the context of growing nationalism, increased militarism, imperial rivalry and competition for power and influence. Europe's leaders were willing to go to war to defend or extend national interests and their choices were shaped by a combination of long and short-term foreign policy goals, political pressures at home, previous crises, and the system of opposing alliances that had developed over the previous 35 years.

The new and unlikely friendship between these three powers heightened German fears of ‘encirclement’ and deepened the divide among the European powers. Imperial rifts worsened these divisions and tensions. When Germany tried to oppose a French takeover of Morocco, Britain supported France.

The assassin was 19-year-old Gavrilo Princip, one of several would-be young assassins who were intent on using violence to destroy Austria-Hungarian rule. Suspecting Serbian backing for the assassination, Austria-Hungary was determined to use the royal murder to crush the Serbian threat once and for all.

Germany's ambitions, its perception of its own isolation and its increasing fear of 'encirclement' drove its foreign policy. The preservation of Austria-Hungary - its only reliable ally - as a great power became an important part of German policy.

Serbia's sovereignty would be destroyed if it accepted the terms in full, but any reply other than unconditional acceptance would give Austria-Hungary its excuse for war. Austria rejected the Serbian reply, which conceded to all the ultimatum's terms except the involvement of Austro-Hungarian officials in an inquiry into the assassination. On 28 July, Austria-Hungary declared war on Serbia. It was determined to take decisive action against Serbia and, by now, knew this risked war with Russia, Serbia's supporter. Austria-Hungary was prepared to risk war because it had the guarantee of German support. The Balkan crisis now threatened a European-wide war.

By the summer of 1914, Germany had only one war plan, which was to knock France out of the war before turning on France's ally, Russia. German politicians saw the Balkan crisis in 1914 as an opportunity to inflict a diplomatic setback on Russia and France, but its Generals feared Russia's growing military power and were ready to strike before it was too late.

On 31 July, Germany sent an ultimatum to Russia demanding it demobilise. The next day, this ultimatum expired without a reply. Germany declared war on Russia and ordered its own general mobilisation. France knew that it faced German invasion, but was clear that it must stand or fall with Russia. Many Frenchmen also hoped that war could settle old grievances with Germany stemming from the 1870s. Germany declared war on 3 August. Throughout the crisis, Russia and France were putting increased pressure on the British to declare their support. But under the terms of its agreements with Russia and France, Britain had no obligation to fight.

But until late July 1914, Britain was largely preoccupied with domestic issues. Social, industrial and political unrest and the threat of civil war in Ireland received most of the nation's attention.

Germany invaded on 4 August.

The poppy is the enduring symbol of remembrance of the First World War. It is strongly linked with Armistice Day (11 November), but the poppy's origin as a popular symbol of remembrance lies in the landscapes of the First World War.

After the outbreak of war in August 1914, Britain recruited a huge volunteer citizens' army. In just eight weeks, over three-quarters of a million men in Britain had joined up. Every volunteer had to undergo a series of medical and fitness tests before being accepted as a soldier. 

On 11 November 1918, an armistice came into effect ending the war in Western Europe – but this did not mean the return of peace. The armistice was effectively a German surrender, as its conditions ended any possibility of Germany continuing the war. 

Explore our online shop for products inspired by people's experience of conflict.

This retro style enamel mug bears a mantra always worth keeping in mind, 'While there is tea there is hope'.

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