Pearson Edexcel International GCSE in History · 4HI1 · Free · no account needed

The origins and course of the First World War, 1905–18 — timeline

57 dated events from 1882 to 11 November 1918, in the order the course teaches them — every date with the reason it earns marks, grouped by key topic and linked to the lesson that explains it. Option A1 of Pearson Edexcel International GCSE History (4HI1): the alliance system and international rivalry, 1905–14; the growth of tension in Europe, 1905–14; the Schlieffen Plan and deadlock on the Western Front; the war at sea and Gallipoli; the defeat of Germany.

A date on its own is a fact; a date with its consequence is an argument. Each entry below therefore carries the authored line on why it matters — what it caused, ended or made possible — because that is the half the examiner pays for. Use the timeline to see the shape of the period; then open the lesson behind any date, understand it, prove it in marked questions, teach it back to an AI pupil and defend it in a structured debate. Completely free.

Key topic 1 · The alliance system and international rivalry, 1905–14

The Triple Alliance and the Triple Entente

1882
The Triple Alliance: Germany, Austria-Hungary and Italy. Why this date: The formal treaty, and the one member that did not honour it in 1914.
1890
The Reinsurance Treaty with Russia is allowed to lapse. Why this date: The German decision that made the Franco-Russian alliance possible four years later.
1894
The Franco-Russian military convention. Why this date: A republic and an autocracy allied because both feared the same power — evidence that interest, not ideology, built the blocs.
1904 and 1907
The Entente Cordiale and the Anglo-Russian Convention. Why this date: Colonial settlements, not defensive alliances, which is the distinction the whole strand turns on.

Economic, imperial and military rivalry

1898 and 1900
German Navy Laws under Tirpitz. Why this date: The decision to build a battle fleet against the one power that could not tolerate one.
1906
HMS Dreadnought launched. Why this date: It made the race countable, which made it public and political.
1909
The British naval scare: we want eight and we won't wait. Why this date: Evidence that the race was driven by domestic politics as much as by strategy.
1913–14
France's Three Year Law and Russia's Great Programme. Why this date: The land race, and the German perception of a closing window before 1917.

Key topic 2 · The growth of tension in Europe, 1905–14

Balkan nationalism, the Bosnian Crisis and the Balkan Wars

1903
The coup in Belgrade brings an anti-Austrian dynasty to power. Why this date: Serbia's orientation changes, and Austro-Serbian rivalry becomes the central Balkan problem.
1908–09
Austria-Hungary annexes Bosnia; Germany forces Russia to accept it. Why this date: Russia's humiliation, and the reason a second climbdown in 1914 was politically impossible.
1912–13
The Balkan Wars; Serbia roughly doubles in size. Why this date: The change in the balance that made Vienna decide the problem needed a military solution.
1913
Albania created to deny Serbia the Adriatic. Why this date: A great-power settlement that satisfied nobody and left Serbia landlocked and resentful.
March 1905
Wilhelm II at Tangier; Germany demands a conference. Why this date: The first test of the Entente, chosen when Russia was weakest.
1906
Algeciras: Germany supported only by Austria-Hungary; Anglo-French military conversations begin. Why this date: Isolation and a British commitment produced by an attempt to prevent both.
July 1911
The Panther at Agadir; Lloyd George's Mansion House speech. Why this date: The speech's author is the point: from the leading anti-confrontation minister it read as a national position.
1912
The Haldane Mission fails; the naval race effectively ends. Why this date: Anglo-German relations improved after 1912, which complicates any simple naval-race explanation of 1914.

Sarajevo and the July Crisis

28 June 1914
Franz Ferdinand assassinated by Gavrilo Princip. Why this date: The occasion. Five weeks separate it from the outbreak, and those weeks contain the decisions.
5 July 1914
The German blank cheque to Austria-Hungary. Why this date: Unconditional backing given before the demands were drafted or the reply known.
23–25 July 1914
The ultimatum with a 48-hour limit; Serbia accepts all but one clause; relations are broken within the hour. Why this date: The single most quotable sequence in the option.
30 July 1914
Russian general mobilisation. Why this date: The decision that made German mobilisation, and therefore the invasion of Belgium, near-automatic.
4 August 1914
Germany invades Belgium; Britain declares war. Why this date: The 1839 treaty gave a divided Cabinet the one ground on which it could unite.

Key topic 3 · The Schlieffen Plan and deadlock on the Western Front

The Schlieffen Plan and why it failed

1905
Schlieffen's memorandum. Why this date: The document the plan is reconstructed from, and the object of the historiographical dispute.
4–16 August 1914
Liège holds for about eleven days. Why this date: The first delay, and it is measured in days rather than the weeks often claimed.
17–20 August 1914
Russia invades East Prussia within about ten days of mobilising. Why this date: The assumption that fails hardest, and it produces the transfer of two corps west to east.
6–9 September 1914
First Battle of the Marne; Kluck turns inside Paris; Hentsch orders withdrawal. Why this date: The plan ends here, five weeks in, and the war of movement ends with it.

Trenches, new weapons and the reasons for deadlock

November 1914
The line reaches the Channel; there is no flank left. Why this date: Deadlock begins as a geographical fact rather than a tactical failure.
April 1915
First large-scale use of chlorine gas at Second Ypres. Why this date: The first attempt at a technological solution, and respirators followed within months.
September 1916
Tanks first used at Flers-Courcelette. Why this date: Small numbers, unreliable; the date matters more than the effect.
November 1917
Cambrai: nearly 400 tanks break the Hindenburg Line and the ground is lost again. Why this date: Break-in without exploitation, which is the deadlock's mechanism demonstrated in one battle.

The Somme, Passchendaele and the responsibility of Haig

February–December 1916
Verdun; the French army is consumed and the Somme's purpose changes. Why this date: The Somme cannot be judged without Verdun, because relief of Verdun became its main purpose.
1 July 1916
About 57,470 British casualties, 19,240 killed. Why this date: The worst day in British military history, and the figure must be given accurately.
November 1916
The Somme closes after an advance of about six miles. Why this date: The ground gained and the German assessment of their own losses both belong in the judgement.
June 1917
Messines: nineteen mines under the ridge, a clear success. Why this date: It shows what the same command could do with limited objectives and adequate preparation.
31 July – 6 November 1917
Third Ypres; the wettest August in decades; Passchendaele taken. Why this date: The weather is a fact about the decision to continue, not an excuse for it.

Key topic 4 · The war at sea and Gallipoli

Heligoland Bight, Dogger Bank and Jutland

August 1914
Heligoland Bight; the Kaiser restricts fleet operations. Why this date: German caution after a small British success shapes the next two years.
December 1914
Coastal raids on Scarborough, Hartlepool and Whitby; around 130 civilians killed. Why this date: Militarily trivial and a substantial propaganda and recruiting effect.
January 1915
Dogger Bank; Blücher sunk; Germany fixes a flash defect Britain does not. Why this date: The direct technical cause of the British battlecruiser losses at Jutland.
31 May – 1 June 1916
Jutland: Britain loses more, Germany withdraws and stays in port. Why this date: The battle whose result depends entirely on the criterion chosen.
January 1917
Germany resumes unrestricted submarine warfare. Why this date: The consequence of concluding that the surface fleet could not break the blockade.

The U-boat threat, the Lusitania and the convoy system

February 1915
Germany declares the waters around Britain a war zone. Why this date: The abandonment of prize rules, which is the legal and moral turn.
7 May 1915
Lusitania sunk; about 1,198 dead including 128 Americans. Why this date: The event that made American opinion a factor in German naval planning.
January–February 1917
Unrestricted submarine warfare resumed; the Zimmermann Telegram intercepted. Why this date: A deliberate gamble on a five-month timetable, and the intelligence that ended it.
April 1917
About 869,000 tons sunk, the worst month of the war. Why this date: The crisis point that forced the change of method.
May 1917
Convoy introduced; losses fall sharply. Why this date: The answer, and it had been available for two years.

Gallipoli: reasons, features, evacuation and effects

March 1915
The naval attempt fails; three battleships lost to an unswept minefield. Why this date: The failure that gave the defenders five weeks and made surprise impossible.
25 April 1915
Landings at Helles and Anzac Cove; Kemal holds the high ground. Why this date: The date commemorated as Anzac Day, and the moment the campaign's outcome was effectively set.
August 1915
The Suvla Bay landing achieves surprise and is not exploited. Why this date: The last chance, lost to the same exploitation problem as the Western Front.
December 1915 – January 1916
Evacuation of around 105,000 men with almost no casualties. Why this date: The one success, and the pairing that makes the strand's argument.

Key topic 5 · The defeat of Germany

The significance of US entry

1 February 1917
Germany resumes unrestricted submarine warfare. Why this date: The decision that made American entry likely, taken in the knowledge that it would.
March 1917
The Zimmermann Telegram published; the February Revolution in Russia. Why this date: The first converted opinion; the second removed the autocratic ally from Wilson's argument.
6 April 1917
The United States declares war. Why this date: The date, and the near-absence of American troops for a year afterwards.
March 1918
Brest-Litovsk releases German divisions; the Spring Offensive opens on 21 March. Why this date: The window, and the reason Ludendorff attacked when he did.

The Ludendorff offensive and the Hundred Days

21 March 1918
Operation Michael; up to sixty kilometres gained; Fifth Army breaks. Why this date: The largest advance since 1914, and it produced the unified command the Allies had refused for three years.
March–July 1918
Five offensives; around a million German casualties; the stormtroopers spent. Why this date: Ground taken and best troops lost — the trade that decided the war.
8 August 1918
Amiens: over 400 tanks, no preliminary bombardment, about eleven kilometres on the first day. Why this date: The black day, named for the surrenders rather than the ground.
29 September 1918
Ludendorff demands an immediate armistice; Bulgaria leaves the war. Why this date: The military decision that produces the German political revolution five weeks later.
11 November 1918
Armistice, with German troops still outside Germany. Why this date: The fact that made the stab-in-the-back myth credible to those who had not seen the front.

From the date to the argument

Every lesson linked above ends by asking you to explain the argument to Ember, an AI pupil who asks the awkward question, and defend it against the historical figure with the strongest claim on it.