Europe divides into two camps

By the early 1900s the great powers had split into two rival alliances. Each promised to help its partners if attacked, so a small quarrel could drag everyone into war:

• The Triple Alliance (1882) — Germany, Austria-Hungary and Italy.
• The Triple Entente (1907) — Britain, France and Russia.

Other long-term tensions pushed the powers apart:

• Militarism — a naval arms race between Britain and Germany over Dreadnought battleships.
• Imperialism — rivalry over colonies, seen in the Moroccan Crises (1905 and 1911).
• Nationalism — especially Slav nationalism in the Balkans, where Serbia challenged Austria-Hungary.

The alliance system did not cause the war on its own, but it meant that once Austria-Hungary and Serbia clashed in 1914, the whole continent could be pulled in.

The "powder keg" of Europe

The Balkans were the most dangerous region in Europe. As the old Ottoman Empire declined, new states like Serbia grew, hoping to unite the Slav peoples.

• In 1908 Austria-Hungary annexed Bosnia, which had a large Serb population. Serbia was furious.
• Serbia wanted to expand and lead the Slavs; Austria-Hungary saw Serbia as a threat to its multi-ethnic empire.
• Russia backed fellow Slavs in Serbia; Germany backed Austria-Hungary. The alliances turned a local dispute into a great-power quarrel.

Historians call the Balkans the "powder keg" of Europe — a region so tense that a single spark could set off a general war. In 1914 that spark came in Sarajevo.

Which alliance?

The assassination of Franz Ferdinand

On 28 June 1914, the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, was shot dead in Sarajevo (in Bosnia) along with his wife Sophie.

• The killer was Gavrilo Princip, a young Bosnian Serb linked to the Black Hand, a secret Serbian nationalist group.
• The plot aimed to break Austria-Hungary's grip on the Slav lands of the Balkans.
• Austria-Hungary blamed Serbia and saw a chance to crush it once and for all.

Key date: the assassination on 28 June 1914 was the trigger — the immediate cause that set off the July Crisis. The long-term causes (alliances, militarism, Balkan tension) made a big war possible.

From murder to world war

The month after the assassination — the July Crisis — is how one murder became a continental war. Step by step, the alliances kicked in:

• Germany gave Austria-Hungary a "blank cheque" — full backing for whatever it did to Serbia.
• Austria-Hungary sent Serbia a harsh ultimatum; when Serbia did not fully accept it, Austria-Hungary declared war on Serbia (28 July 1914).
• Russia mobilised to defend Serbia; Germany declared war on Russia (1 Aug) and then on France (3 Aug).
• Germany invaded neutral Belgium to reach France — so Britain declared war on Germany on 4 August 1914.

Britain entered partly because of the 1839 Treaty of London, which guaranteed Belgian neutrality. Germany dismissed it as a "scrap of paper" — but for Britain it was a reason to fight.

Date the spark

Germany's plan to avoid a two-front war

Germany's greatest fear was a war on two fronts — France in the west and Russia in the east at the same time. The Schlieffen Plan was its answer.

• Attack France first, sweeping through Belgium to defeat France in about six weeks.
• Then move the army east to fight Russia, which was expected to be slow to mobilise.

The plan relied on speed. But invading Belgium brought Britain into the war, and Russia mobilised faster than expected — so Germany faced exactly the two-front war it had tried to avoid.

The Marne stops the plan

The German advance drove deep into France, but was halted just short of Paris at the First Battle of the Marne in September 1914.

• French and British forces counter-attacked and pushed the Germans back to the River Aisne.
• The Schlieffen Plan had failed — France was not knocked out quickly, and Germany now faced war on two fronts.
• Both sides dug trenches to hold their ground. The "race to the sea" extended these trenches until a line ran from the English Channel to Switzerland.

Why the Marne mattered: it ended any hope of a short war of movement and began the long stalemate of trench warfare on the Western Front.

Why the plan failed

Life and death in the trenches

By the end of 1914 the Western Front was a system of trenches facing each other across "no man's land". Neither side could break through.

• Defence beat attack: machine guns, barbed wire and artillery made charging across no man's land almost suicidal.
• Soldiers endured mud, rats, lice, disease and "trench foot", plus the terror of shelling and poison gas (first used on a large scale in 1915).
• New weapons — the tank (first used at the Somme, 1916) and aircraft — were tried to break the deadlock.

Attrition: unable to break through, generals turned to a war of attrition — trying to wear the enemy down by inflicting more casualties than they suffered.

The Battle of Verdun

In 1916 the Germans attacked the French fortress town of Verdun, aiming to "bleed France white" — to draw the French army into a battle it could not afford to lose.

• The battle lasted from February to December 1916 — nearly the whole year.
• Both sides suffered enormous casualties (together, around 700,000 killed and wounded) for very little ground.
• The French held on under the slogan "They shall not pass" (Ils ne passeront pas).

Verdun became a symbol of French endurance — and of the terrible cost of a war of attrition where victory was measured in casualties, not miles.

The Battle of the Somme

The British launched the Battle of the Somme partly to relieve pressure on the French at Verdun. It ran from 1 July to November 1916.

• A week-long artillery bombardment failed to destroy the German barbed wire and deep dugouts.
• On the first day, 1 July 1916, the British suffered around 57,000 casualties (about 19,000 killed) — the bloodiest day in British Army history.
• The battle saw the first ever use of tanks (September 1916) but they were few and unreliable.
• By November the Allies had advanced only a few miles at a cost of over a million casualties on all sides.

Year of the big battles

The war at sea

Britain and Germany had built huge navies before the war. Sea power mattered because Britain relied on imported food and supplies.

• Blockade: the British navy blockaded Germany, cutting off supplies and slowly starving its people.
• Battle of Jutland (1916): the one great clash of the main fleets in the North Sea. It was indecisive, but afterwards the German High Seas Fleet mostly stayed in port — a strategic win for Britain.
• U-boats: Germany used submarines to sink merchant ships. Unrestricted submarine warfare and the sinking of the Lusitania (1915) angered the USA. Britain answered with the convoy system, grouping ships together for protection.

The German submarine campaign helped push the USA towards war. America declared war on Germany in April 1917, bringing fresh troops and resources to the Allies.

Gallipoli, 1915

To break the deadlock, the Allies tried to open a new front against Germany's ally the Ottoman Empire (Turkey). The plan was to seize the Dardanelles straits and help Russia.

• In 1915 Allied troops (including many ANZACs — Australians and New Zealanders) landed on the Gallipoli peninsula.
• The Turks held the high ground; the campaign became another bloody stalemate.
• After heavy losses the Allies evacuated in early 1916. Gallipoli was a costly failure.

Gallipoli showed how hard it was to find a "back door" around the Western Front — attempts to break the stalemate elsewhere often failed too.

Which was the failure?

Battle / event ↔ significance

Tap an event on the left, then tap its significance on the right.

Russia out, America in

1917 changed the balance of the war in two huge ways:

• The Bolshevik Revolution in Russia (1917) led to Russia leaving the war. The Treaty of Brest-Litovsk (March 1918) made peace between Russia and Germany, freeing German troops to move west.
• The USA entered the war in April 1917, provoked by unrestricted submarine warfare and the Zimmermann Telegram. Fresh American troops and supplies began pouring into France in 1918.

Germany knew it had to win quickly in 1918 — before the full weight of American forces arrived and while it had extra troops from the Eastern Front.

Germany's last gamble

In spring 1918 Germany launched a massive attack to win before the Americans arrived in force:

• The Spring Offensive (Ludendorff Offensive), March 1918 — Germany advanced far and fast, but exhausted its troops and could not land a knockout blow.
• The Allies, now strengthened by American troops and using tanks and better tactics, counter-attacked in the Hundred Days Offensive from August 1918.
• The German army was pushed back and its allies (Bulgaria, Ottoman Empire, Austria-Hungary) began to collapse.

By autumn 1918 Germany was exhausted: the blockade caused starvation at home, the army was retreating, and there were mutinies and unrest.

The Armistice

With defeat certain, Germany's Kaiser Wilhelm II abdicated and a new German government asked for peace.

• The Armistice was signed on 11 November 1918, ending the fighting.
• It came into effect at 11 a.m. — the eleventh hour of the eleventh day of the eleventh month.
• The formal peace terms came later in the Treaty of Versailles (1919).

Misconception alert: the Armistice was a ceasefire, not a full peace treaty. Germany had not been invaded, which later fed the "stab in the back" myth — the false idea that the army had been betrayed at home rather than beaten.

The day the guns fell silent

Name the town

Timeline: 1894 → 1918

Put the events in order

Tap the events in the correct time order, from earliest to latest.

Working with sources

AQA's Conflict and Tension paper asks you to use sources. Two habits win marks:

• Judge the source's usefulness by its content and its provenance — who made it, when, and why (a recruitment poster is designed to persuade, not to inform neutrally).
• Bring in your own knowledge — support or challenge a source using facts you know about the events.

Exam tip: a wartime propaganda poster is still useful — it shows how governments tried to influence people. "Biased" does not mean "useless"; explain what it is useful for.

Thinking like a historian

Why Britain joined

The essentials to remember

You've covered the whole AQA Conflict and Tension: The First World War, 1894-1918 study. Press Finish to see your score.