What you'll learn
This revision guide covers the OCR GCSE History World Depth Study on the First World War, 1914–18. You'll examine the origins of the conflict, the nature of trench warfare on the Western Front, major offensives including the Somme and Passchendaele, and the events leading to Germany's defeat in 1918. The guide focuses on testable content with exam-ready explanations and authentic historical detail.
Key terms and definitions
Alliance system — the network of defensive agreements between European powers (Triple Alliance: Germany, Austria-Hungary, Italy; Triple Entente: Britain, France, Russia) that turned a regional crisis into a continental war.
Schlieffen Plan — Germany's pre-war strategy to defeat France quickly through Belgium before Russia could mobilise, avoiding a two-front war.
Attrition — a military strategy of wearing down the enemy through continuous losses in personnel and materiel, famously declared by Haig as Britain's approach at the Somme.
No Man's Land — the devastated, often cratered ground between opposing trenches, typically 50–250 metres wide, swept by machine-gun fire and artillery.
Stalemate — the military deadlock on the Western Front from late 1914 to 1918, where neither side could achieve a decisive breakthrough despite massive offensives.
U-boat — German submarine (Unterseeboot) used to blockade Britain by sinking merchant shipping, including neutral vessels, contributing to America's entry into the war.
Creeping barrage — an artillery technique where shells landed just ahead of advancing infantry, introduced to provide cover during attacks.
Armistice — the ceasefire agreement signed on 11 November 1918 that ended fighting on the Western Front at 11am, though a formal peace treaty came later at Versailles.
Core concepts
The causes of the First World War, 1914
The immediate trigger was the assassination of Archduke Franz Ferdinand in Sarajevo on 28 June 1914 by Gavrilo Princip, a Bosnian Serb nationalist. Austria-Hungary blamed Serbia and issued an ultimatum on 23 July. Serbia's partial acceptance was rejected, and Austria-Hungary declared war on 28 July.
The alliance system then activated:
- Russia mobilised to support Serbia (fellow Slavs)
- Germany declared war on Russia (1 August) and France (3 August)
- Germany invaded neutral Belgium to execute the Schlieffen Plan
- Britain declared war on Germany (4 August) due to treaty obligations to Belgium
Long-term causes included:
Militarism — arms races, particularly the Anglo-German naval rivalry, and glorification of military strength created tension and made war planning automatic.
Imperialism — competition for colonies, especially in Africa and the Balkans, caused friction between powers seeking resources and prestige.
Nationalism — fervent patriotism and desire for independence (particularly in the Balkans) destabilised multi-ethnic empires like Austria-Hungary.
The Schlieffen Plan failed because Belgium resisted longer than expected, Britain's intervention was swift, and Russia mobilised faster than predicted. German forces were stopped at the First Battle of the Marne (September 1914), leading to the Race to the Sea as both sides attempted to outflank each other northward.
The Western Front and trench warfare
By November 1914, continuous trench lines stretched from the English Channel to Switzerland, approximately 475 miles. This created the characteristic stalemate that defined the Western Front.
Trench systems consisted of three main lines:
- Front-line trenches facing the enemy
- Support trenches 80–100 metres behind
- Reserve trenches further back
Trenches zigzagged to prevent enfilade fire and limit blast damage. Communication trenches connected the lines. Dugouts provided shelter from bombardment.
Conditions in the trenches were appalling:
- Waterlogged trenches caused trench foot, a painful condition from prolonged immersion
- Rats fed on corpses and spread disease
- Lice caused trench fever, a debilitating illness
- Limited sanitation led to dysentery and typhoid
- Constant shelling caused psychological trauma, known as shell shock
Daily routines included "stand-to" at dawn and dusk (periods of heightened alert), sentry duty, maintenance of trenches and barbed wire, and rotating between front-line and reserve positions every few days.
New weapons and technology
The industrialised nature of the First World War introduced weapons that made defensive positions virtually impregnable:
Machine guns (particularly the German MG08 and British Vickers) could fire 450–600 rounds per minute, making infantry advances suicidal. A single gun could cover no man's land effectively.
Artillery caused approximately 60% of casualties. Heavy guns bombarded enemy trenches for days before major offensives, but often failed to destroy defences or cut barbed wire. Shrapnel shells were effective against troops in the open.
Poison gas was first used by Germany at Ypres in April 1915. Chlorine, phosgene and mustard gas caused choking, blindness and chemical burns. Gas masks were developed in response, but gas remained a psychological weapon.
Tanks were introduced by Britain at the Somme in September 1916. Early models (Mark I) were slow, unreliable and vulnerable to breakdowns, but they could cross trenches and crush barbed wire. By 1917–18, improved tactics and reliability made them more effective.
Aircraft evolved from reconnaissance to fighters and bombers. The "Fokker Scourge" (1915–16) saw German aircraft dominate until Allied improvements restored balance. Aerial photography aided artillery targeting.
The Battle of the Somme, 1916
Launched on 1 July 1916, the Somme offensive aimed to relieve pressure on the French at Verdun and break through German lines.
Planning and preparation:
- Seven-day artillery bombardment fired 1.7 million shells
- General Haig believed German defences would be destroyed
- British troops were largely volunteers from Kitchener's New Army, with limited training
1 July 1916 — the bloodiest day:
- British forces advanced at walking pace carrying 60lb packs
- German defenders emerged from deep dugouts and manned machine guns
- 57,470 British casualties (19,240 dead) on the first day
- Some units lost 90% of their men in the first hour
The offensive continued until November 1916:
- Tactical adjustments included smaller-scale attacks and night operations
- Tanks used for the first time (15 September)
- Total casualties: approximately 420,000 British, 200,000 French, 465,000 German
- Territorial gain: approximately 6 miles at maximum advance
Debate over the Somme:
- Critics argue it was futile slaughter with negligible gains
- Defenders claim it was attrition warfare that weakened Germany fatally
- German army was forced to reorganise and retreat to the Hindenburg Line in 1917
The Battle of Passchendaele (Third Battle of Ypres), 1917
Launched 31 July 1917, this offensive aimed to break through in Flanders and capture Belgian ports used by German U-boats.
Conditions:
- Unprecedented rainfall turned the battlefield into a swamp
- Shell holes filled with water; men and horses drowned in mud
- Tanks became stuck and useless
- Wounded soldiers drowned in craters before stretcher-bearers could reach them
Progress:
- Advances measured in hundreds of yards
- Pillboxes (concrete German strongpoints) proved resistant to bombardment
- Limited success at Messines Ridge in June (mine warfare destroyed German positions)
- Passchendaele village finally captured by Canadian forces (6 November)
Outcome:
- Approximately 325,000 British and Commonwealth casualties
- German casualties estimated at 260,000
- Territorial gain: approximately 5 miles
- Widely regarded as exemplifying the futility of attritional warfare
- Damaged morale and reinforced anti-war sentiment at home
America's entry and Germany's defeat, 1918
Why America entered the war (April 1917):
- Unrestricted U-boat warfare sank American merchant ships
- The sinking of the Lusitania (1915, 128 Americans killed) had angered American public opinion
- The Zimmermann Telegram (January 1917) revealed German plans to ally with Mexico against the USA
- Economic ties to Britain and France (loans and trade) created financial interest in Allied victory
The German Spring Offensive (March–July 1918):
- Russia's exit after the Treaty of Brest-Litovsk (March 1918) freed German troops for the Western Front
- Operation Michael (21 March) achieved initial breakthrough using stormtrooper tactics
- Gained 40 miles, the largest advance since 1914
- Exhausted German forces lacked reserves and supplies
- Paris came under artillery fire, but the offensive stalled
Allied counter-offensive (August–November 1918):
- The Hundred Days Offensive coordinated British, French, American and Commonwealth forces
- Battle of Amiens (8 August) — "the black day of the German army" — used massed tanks effectively
- Breaking of the Hindenburg Line in September ended German defensive capability
- German allies (Bulgaria, Ottoman Empire, Austria-Hungary) collapsed
Why Germany sought an armistice:
- Naval mutiny at Kiel (October 1918) sparked revolution
- Kaiser Wilhelm II abdicated (9 November)
- Economic exhaustion and food shortages (British naval blockade)
- Military defeat inevitable with American reinforcements arriving
- Home front morale collapsed
The armistice was signed in a railway carriage at Compiègne on 11 November 1918, ending the war at 11am.
Worked examples
Example 1: "Explain why the Schlieffen Plan failed in 1914." [6 marks]
Model answer: The Schlieffen Plan failed primarily because Belgium resisted German invasion longer than expected, delaying the advance through neutral territory toward France. The Belgian army destroyed railways and bridges, whilst the fortress of Liège held out for twelve days, disrupting German timetables. This delay allowed Britain to deploy the British Expeditionary Force, which fought at Mons and slowed the German advance further.
Additionally, Russia mobilised faster than Germany anticipated, forcing Germany to divert troops eastward to defend against Russian invasion. This weakened the right wing of the advance through Belgium, which was crucial to the plan's success. General von Moltke reduced forces in the west, undermining the strategy.
Finally, exhausted German forces were stopped at the First Battle of the Marne when French and British troops counter-attacked. Paris taxis famously transported reinforcements to the battle. The German retreat to the Aisne River ended hopes of quick victory, leading to trench warfare.
Mark scheme guidance: This answer provides three distinct reasons with supporting detail (Belgian resistance, Russian mobilisation, Battle of the Marne), demonstrating causal understanding required for 6 marks.
Example 2: "How useful is Source A for studying conditions in the trenches?" [8 marks]
(Assume Source A is a photograph of British soldiers in a flooded trench, 1916)
Model answer approach: Provenance analysis: The source is a photograph from 1916, showing first-hand visual evidence of trench conditions. As an official photograph, it may have been censored to maintain morale, limiting usefulness. However, the visible flooding supports written accounts of waterlogged trenches.
Content analysis: The source shows several soldiers standing in water up to their knees, demonstrating the flooding that caused trench foot. The trench walls appear unstable with sandbag reinforcement visible, confirming maintenance difficulties. This is useful for understanding the physical hardship soldiers endured.
Limitations: The photograph shows only one moment and location; conditions varied along the 475-mile front. It cannot show smells, disease, rats or lice, which were equally important aspects of trench life. Soldiers may have posed, making it less natural. The source doesn't show combat conditions or psychological effects like shell shock.
Contextual knowledge: The source should be compared with other evidence such as soldiers' letters, medical records showing trench foot cases, and diaries describing daily routines, to build a fuller picture.
Mark scheme guidance: Top-level answers evaluate usefulness by analysing both strengths and limitations, using provenance and contextual knowledge, not just describing content.
Common mistakes and how to avoid them
Confusing causes with consequences — Students often muddle why the war started with what happened during it. Remember: alliance system and assassination are causes; stalemate and new weapons are features of the war itself.
Lack of specific detail — Saying "the Somme was bad" earns no marks. Use precise facts: "57,470 British casualties on 1 July 1916" demonstrates knowledge. Learn key dates, statistics and names.
Narrative instead of analysis — Simply describing what happened ("first this, then that") won't access higher marks. Explain why events occurred and their significance. Use connectives: "consequently," "this led to," "as a result."
Ignoring the question — If asked about failure of the Schlieffen Plan, don't write everything you know about it. Focus specifically on reasons for failure: Belgian resistance, Russian mobilisation, Battle of the Marne.
Weak source evaluation — Don't just describe source content. Analyse provenance (who created it, when, why) and test content against your own knowledge. Consider purpose, audience and limitations.
One-sided arguments — In evaluation questions, consider different perspectives. The Somme can be viewed as both futile slaughter and necessary attrition. Show you understand historical debate.
Exam technique for "World Depth Study: The First World War, 1914–18"
Master command words: "Explain why" requires causes with supporting detail (6 marks typically needs 2–3 reasons). "How far do you agree" demands a balanced argument with judgement (10 marks requires sustained analysis with counter-argument).
Source questions need BOTH analysis AND knowledge: Don't just paraphrase sources. Evaluate reliability using provenance, cross-reference with other sources if provided, and test against your contextual knowledge. An 8-mark usefulness question requires detailed analysis of strengths and limitations.
Plan extended writing: For 10-mark questions, spend 2–3 minutes planning. Structure: introduction stating your line of argument, 3–4 paragraphs with different factors/perspectives, conclusion with overall judgement. Link paragraphs with comparative language: "However, a more significant factor was..."
Use historical terminology accurately: Demonstrate sophistication with terms like stalemate, attrition, armistice, rather than vague language. Quote historians or historical phrases where appropriate ("war of attrition" vs "killing lots of people").
Quick revision summary
The First World War began in 1914 due to alliance systems activating after Franz Ferdinand's assassination. The Schlieffen Plan's failure created stalemate on the Western Front, where trench warfare dominated until 1918. New technology (machine guns, artillery, poison gas, tanks) made defence dominant, causing massive casualties at the Somme (1916) and Passchendaele (1917) with minimal gains. Germany's Spring Offensive (1918) failed, and Allied counter-attacks, strengthened by American entry, forced Germany to seek an armistice on 11 November 1918. Understanding causes, key battles, technology, and reasons for Germany's defeat is essential for exam success.