A timeline, 1905 → 1918

Keep this shape in your head. The dates on the left are causes and crises; the dates on the right are the war itself.

Europe split into two armed camps

By 1907 the great powers had lined up behind two rival alliances. A quarrel between any two members could drag in all the others.

Key detail: the Triple Alliance (Germany, Austria-Hungary, Italy) was signed in 1882. The Triple Entente grew from the Franco-Russian alliance, the 1904 Entente Cordiale (Britain–France) and the 1907 Anglo-Russian agreement.

Who was in which camp?

The M.A.I.N. long-term causes

Historians group the deep causes of rivalry under four headings. Learn them with the trigger that set them off.

Misconception: the assassination was the trigger, not the sole cause. Without the arms race, alliances, imperial rivalry and Balkan nationalism already built up over years, one murder would not have caused a world war.

Militarism & the naval race

Militarism means glorifying military strength and letting generals shape policy. Armies grew, and Germany and Britain raced to build the biggest navy.

• Britain launched HMS Dreadnought in 1906 — a huge, fast, "all-big-gun" battleship that made every older warship out of date.
• Germany's Kaiser Wilhelm II wanted a world-class fleet to rival Britain, so both sides raced to build more dreadnoughts.
• By 1914 Britain had about 29 dreadnoughts to Germany's 17 — Britain kept its lead, but the rivalry bred deep mistrust.

The naval race

Imperial rivalry & the Moroccan Crises

Imperialism — competition for colonies, trade and prestige — kept the powers at each other's throats. Twice, Germany challenged France in Morocco to test the Entente.

• First Moroccan Crisis, 1905: Kaiser Wilhelm II visited Tangier and backed Moroccan independence to weaken French influence. At the Algeciras Conference (1906) Germany was isolated — Britain backed France, drawing the Entente closer.
• Second (Agadir) Crisis, 1911: Germany sent the gunboat Panther to Agadir to pressure France. Again Britain stood by France. Germany gained some land in the Congo but looked like a bully.

Significance: both crises backfired on Germany. Instead of splitting Britain and France, they pushed the Entente closer together and left Germany feeling "encircled".

Your turn — the Moroccan Crises

The "powder keg" of Europe

The Balkans were the most dangerous region in Europe. The old Ottoman Empire was collapsing, new nations were forming, and two great powers wanted control:

• Russia supported Slav peoples in the Balkans (pan-Slavism) and wanted access to warm-water ports.
• Austria-Hungary feared that Balkan nationalism — especially a strong Serbia — would break up its own multi-ethnic empire.
• Bosnian Crisis, 1908: Austria-Hungary annexed Bosnia. This angered Serbia (which wanted the Serbs there) and humiliated Russia, which had to back down.
• Balkan Wars, 1912-13: made Serbia bigger and more confident — and Austria-Hungary more determined to crush it.

Why it mattered: Austro-Serbian rivalry, backed by Russia behind Serbia and Germany behind Austria, meant a local Balkan quarrel could trigger the whole alliance system.

The Bosnian Crisis, 1908

Sarajevo, 28 June 1914

The heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife visited Sarajevo in Bosnia. A group linked to the Serbian nationalist "Black Hand" plotted to kill him.

• An early bomb attempt failed. Later, the driver took a wrong turn — and Gavrilo Princip, a young Bosnian Serb, shot the Archduke and his wife dead at close range.
• Austria-Hungary blamed Serbia and saw a chance to crush it. Germany gave Austria a "blank cheque" — unconditional backing.

Misconception reminder: Sarajevo was the spark. The "powder keg" of alliances, militarism, imperial rivalry and Balkan nationalism had been filling for years — that is why one assassination escalated into a world war.

The July Crisis, 1914

In the weeks after Sarajevo, the alliance system turned a Balkan quarrel into a continental war. Follow the chain:

The Schlieffen Plan

Germany faced war on two fronts — France in the west, Russia in the east. The Schlieffen Plan was its solution: knock out France fast (in about six weeks) through Belgium, then turn to fight the slow-mobilising Russians.

Misconception: the Schlieffen Plan failed. Belgian resistance slowed the advance, Britain joined the war over Belgium, Russia mobilised faster than expected, and the German army was halted at the Marne. A quick war became a long one.

Why did the plan fail?

The Marne & the birth of stalemate

At the First Battle of the Marne (September 1914) French and British troops stopped the German advance near Paris. Both sides then tried to outflank each other in the "race to the sea", digging in as they went.

The result was a continuous line of trenches from the English Channel to the Swiss border. Neither side could break through: this was stalemate.

Misconception: stalemate did not come from bad generals alone. It came mainly from defensive technology — the machine gun, barbed wire and artillery gave a huge advantage to defenders, so attacks across "No Man's Land" were slaughtered.

Inside the trenches

Life in the trenches meant mud, rats, disease (like trench foot) and the constant danger of shelling. Here is a labelled cross-section of the front line.

New weapons of the Western Front

The war forced both sides to invent and improve deadly technology to try to break the stalemate:

• Machine guns — fired hundreds of rounds a minute; the deadliest defensive weapon and a main cause of stalemate.
• Poison gas — chlorine (first used by Germany at Ypres, 1915) then mustard gas; horrifying but unreliable (the wind could blow it back).
• Tanks — first used by Britain at the Somme in 1916; slow and unreliable at first, but able to cross trenches and wire. More effective by 1918.
• Aircraft — used for reconnaissance (spotting), then bombing and "dogfights".

Key point: early in the war, technology mostly helped the defender (machine guns, wire). Only by 1918 did tanks, aircraft and better tactics start to break the deadlock.

Your turn — the machine gun

The Somme, 1916, and General Haig

The Battle of the Somme (July–November 1916), led by the British commander General Sir Douglas Haig, aimed to break the German line and relieve the French at Verdun.

• 1 July 1916 was the worst day in British Army history — around 57,000 casualties (about 20,000 dead) in a single day.
• A week-long bombardment failed to cut the wire or destroy German dug-outs, so troops advancing in daylight were machine-gunned down.
• By November the Allies had advanced only a few miles at the cost of over a million casualties on all sides.

Interpretation: historians argue over Haig — the "butcher of the Somme" who wasted lives, or a commander learning hard lessons that helped win the war in 1918. Edexcel wants you to weigh the responsibility of Haig and judge his successes and failures.

Match the event to its significance

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

The war at sea & the Battle of Jutland

Britain's Royal Navy used its strength to blockade Germany, cutting off food and supplies. Germany tried to break out with its High Seas Fleet.

• Battle of Jutland (1916) — the war's only major clash of battle fleets, in the North Sea. Germany sank more ships, but the German fleet retreated to port and stayed there for the rest of the war.
• So Jutland was a tactical draw but a strategic British victory: Britain kept control of the seas and its blockade continued to starve Germany.

Watch the wording: saying "Germany won Jutland because it sank more ships" misses the point — who kept control of the sea mattered more, and that was Britain.

U-boats & unrestricted submarine warfare

Unable to beat the Royal Navy in open battle, Germany used U-boats (submarines) to sink merchant ships bringing supplies to Britain.

• 1915: a U-boat sank the passenger liner RMS Lusitania, killing nearly 1,200 people, including 128 Americans — turning US opinion against Germany.
• 1917: Germany launched unrestricted submarine warfare — sinking any ship, including neutral American ones, without warning.
• Britain fought back with the convoy system (merchant ships escorted by warships), plus depth charges and mines, which cut losses sharply.

Cause & effect: unrestricted submarine warfare backfired — it was a key reason the USA joined the war in April 1917.

Consequences at sea

Gallipoli, 1915

To break the deadlock and help Russia, the Allies attacked the Ottoman Empire (Germany's ally) at Gallipoli, aiming to open a sea route to Russia through the Dardanelles.

• The naval attack failed, so troops (including many ANZACs — Australians and New Zealanders) landed in April 1915.
• The Ottomans held the high ground; the campaign became its own stalemate, with heat, disease and heavy losses.
• After months of failure, the Allies evacuated by January 1916 — ironically the best-run part of the whole operation.

Effects: a costly Allied failure. It damaged reputations (Churchill, who had championed it, lost his post) but forged the ANZAC legend still marked today.

USA in, Russia out

1917 was the turning-point year. Two huge changes reshaped the war:

• USA joins (April 1917) — pushed in by unrestricted submarine warfare and the Zimmermann Telegram (Germany's secret offer to help Mexico attack the USA). America brought fresh troops, money and supplies to the Allies.
• Russia leaves (1917-18) — after two revolutions in 1917, the new Bolshevik (communist) government made peace at the Treaty of Brest-Litovsk (March 1918). Germany could now move troops from the Eastern Front to the West.

Race against time: Germany had a brief window to win in the west before the Americans arrived in force — which set up the great offensive of 1918.

1918: the Spring Offensive & the Hundred Days

• German Spring Offensive (March 1918) — using troops freed from Russia, Germany attacked hard and advanced further than at any time since 1914. But it ran out of supplies and men, and the advance stalled.
• The Allied Hundred Days (Aug–Nov 1918) — now reinforced by the Americans, the Allies counter-attacked, using tanks, aircraft and coordinated tactics to push the exhausted Germans back.
• Germany's allies collapsed, the naval blockade caused starvation and unrest at home, and mutiny broke out in the German navy.

Reasons for German defeat: the failure of the Spring Offensive, the arrival of US forces, the effect of the Allied blockade, and collapse of morale and the Central Powers at home and abroad.

The Armistice, 11 November 1918

With his army in retreat, his allies gone and revolution at home, Kaiser Wilhelm II abdicated. A new German government signed the Armistice (ceasefire) that came into effect at 11 a.m. on 11 November 1918 — the "eleventh hour of the eleventh day of the eleventh month".

Careful: the Armistice was a ceasefire, not the peace treaty. Do not confuse 11 November 1918 (Armistice) with 1919 (Treaty of Versailles).

Put the events in order

Tap the events in the correct order, earliest first. Get one wrong and it resets — so think carefully!

Your turn — causation

Thinking like a historian

The story in a nutshell

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