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World History Stretch · Grade 9

The Twentieth Century

This is the century the modern world came out of, and it opens with a puzzle: how does one assassination on a Sarajevo street end with nine million soldiers dead? By the end of this poster you should be able to argue, with evidence, why institutions and memory are not decorations on history but load-bearing walls.
🔥The Spark Only Matters Because the Room Was Full
This is the single most common error people make about 1914: collapsing the trigger into the cause. The assassination of Archduke Franz Ferdinand in Sarajevo on 28 June 1914 was a match. Europe had spent forty years filling the room.
EUROPE, 1914 — the room 28 JUNE 1914 — the trigger an assassination in Sarajevo ALLIANCES binding promises to defend one another, so a local quarrel obligates everyone in the chain ARMS RACE navies, artillery and mobilization timetables built to be fast — which left almost no time to reconsider IMPERIAL RIVALRY competition over colonies, markets and prestige turned every crisis into a test of national standing NATIONALISM in its aggressive form: the belief that your nation’s greatness is measured against someone else’s loss A trigger explains the timing. A structure explains the size.
⛓Five Weeks From a Street Corner to a Continent
28 JUNE the archduke is assassinated in Sarajevo 28 JULY Austria-Hungary declares war on Serbia 1 AUGUST Germany declares war on Russia 3 AUGUST Germany declares war on France 4 AUGUST Germany invades Belgium; Britain declares war 28 June → 4 August = 37 days Nobody in the chain had to want a continental war. The chain did the work.
🔒The Interwar Hinge
The years between the wars are not a gap. They are the mechanism that connects them — and every link is checkable.
WhenWhat it set up
11 Nov 1918The armistice — an agreement to stop fighting while terms are negotiated. Not a peace treaty. It was written to take effect at 11 a.m. on the eleventh day of the eleventh month, and fighting continued right up to the deadline.
June 1919The Treaty of Versailles finally set the terms, seven months later, including reparations — payments a defeated country must make as compensation for war damage. Inside Germany these became a lasting political grievance.
1920sThe League of Nations was founded to prevent the next war — and was weakened from the start, not least because the United States never joined it. In 1923 German hyperinflation reached the point where a wheelbarrow of marks could not buy a loaf of bread.
From 1929The Great Depression spread worldwide: production collapsed, banks failed, unemployment stayed high for years. Mass unemployment and lost savings made extreme movements promising order far more appealing.
1922 · 1933Fascism took power: Mussolini in Italy in 1922, Hitler as German chancellor in 1933. Extreme nationalism, one all-powerful leader and party, the glorification of force, and the crushing of dissent and minority groups.
Sept 1939Germany invaded Poland, and the Second World War began in Europe. Japan attacked Pearl Harbor in December 1941.
⚠️Handle “Versailles caused World War II” carefully. Treaties do not cast spells — people make choices. Between 1919 and 1933 a great many Germans made political choices under enormous economic pressure, and the treaty is one factor among several. Weighing those factors against evidence, rather than reciting a single cause, is the actual skill this lesson is teaching.
🕯️The Holocaust
The definition, stated precisely The Holocaust was the systematic, state-sponsored persecution and murder of six million European Jews by Nazi Germany and its allies and collaborators between 1933 and 1945. Roma and Sinti, people with disabilities, Poles, Soviet prisoners of war, and others were also targeted for persecution and murder.

This was not a battle, and it was not a byproduct of war. It was a policy, carried out by a modern state with budgets, timetables, memoranda and inventories — a government that kept receipts. In the Second World War as a whole, more civilians died than soldiers.

Six million is a number you cannot picture. That is exactly the problem. It is why serious memory work insists on going the other direction — one name, one birth year, one hometown, one photograph at a time — because a person is a thing you can actually hold in your mind, and a statistic is not.
⚖️Nuremberg: The Argument for a Courtroom
In November 1945, twenty-one senior Nazi officials filed into a courtroom in a building that had somehow survived the bombing that flattened the town around it. The Allies had won six months earlier. What they had not agreed on was what to do with the men who ran the losing side.
THE CASE FOR SHOOTING THEMargued by several senior Allied figures
Everyone already knew what these men had done.
A trial would consume months.
Handing them a courtroom would hand them a microphone.
All three points were practical, and none of them were wrong on their own terms.
THE CASE FOR A TRIALwhich won
Killing prisoners without trial is precisely what the defeated regime had done.
A government that skips the trial has already conceded the argument it claims to be winning.
Four victorious powers — the United States, Britain, France and the Soviet Union — agreed to submit their enemies to judgment rather than vengeance.
Chief prosecutor Robert H. Jackson, a sitting U.S. Supreme Court justice, said the court’s purpose was to “stay the hand of vengeance” — and that the standard applied here must be one we are willing to have applied to ourselves.
📜Built on their own paperworkProsecutors built much of the case out of the regime’s own documents — orders, transport schedules, budget lines, inventories. So the verdict never came down to one survivor’s word against one defendant’s denial.
⚖️The verdictsThe trial ran Nov 1945 – Oct 1946. Twelve defendants were sentenced to death, seven to prison, and three were acquitted — which mattered more than it seems: a court that convicts everyone in front of it is not functioning as a court.
🌐The real legacy: a categoryThe charter named “crimes against humanity” — atrocities against civilian populations, including a government’s own citizens — as offences an international court could try. Before 1945 that was largely a state’s own business. It has never gone back to being one.
📚A New Word for an Old Crime
genos Greek — a people, a tribe + -cide Latin — killing = GENOCIDE coined in a 1944 book Raphael Lemkin, a Polish-Jewish jurist, escaped Europe in 1941; dozens of his family did not survive the Holocaust. He named the crime — the deliberate destruction of a group, targeted not for anything its members did but for who they were. Then he spent the rest of the decade lobbying diplomats one at a time. 9 DECEMBER 1948 the UN adopts the Genocide Convention 10 DECEMBER 1948 and the Universal Declaration of Human Rights
Two documents, two days, one underlying claim: there are things no government may do to any human being, and this is a matter of law rather than of taste. The UDHR was drafted by a committee chaired by Eleanor Roosevelt.
⚖️Rules Are Not the Same as Enforcement
It would be a comfortable story if it ended at 1948. It does not — and this is exactly where the history usually gets flattened in both directions at once.
✗The honest failureThe Genocide Convention did not prevent the mass killings in Cambodia in the 1970s, in Rwanda in 1994, or at Srebrenica in 1995. In several of those cases, governments that had signed the treaty spent weeks arguing over whether the word applied — in part because saying it out loud implied an obligation to act. A rule without enforcement is a promise, and promises get broken.
✓And the honest counterweight“Imperfect” and “useless” are different words. The international tribunals for the former Yugoslavia and for Rwanda in the 1990s convicted heads of state, generals and government ministers using legal categories invented at Nuremberg. The International Criminal Court, opened in 2002, exists because that 1945 courtroom existed first. None of this undoes a single death. All of it changes what a government has to expect.
⏳The Century in One Line
1910 2000 1914 the First World War 1939 war in Europe begins 1989 the Berlin Wall falls 1929 the Depression 1945 war ends · UN founded 1960 Year of Africa 1918 armistice 1933 Hitler chancellor 1991 Soviet Union ends 1948 Genocide Convention DECOLONIZATION — 1945 to the mid-1970s THE COLD WAR — roughly 1947 to 1991
Drawn to scale. Notice how tightly the catastrophes cluster — and that the institutions were built in the same decade as the worst of it.
🌍Cold War, and a World of New Countries
♛Why “cold”The United States and the Soviet Union never fought each other directly. They competed through alliances, a nuclear arms race, propaganda, espionage and proxy wars — which is a description of the two superpowers’ relationship, not a claim that the era was peaceful. It was not.
🏴DecolonizationColonies across Asia and Africa became independent nations, concentrated between 1945 and the mid-1970s. India and Pakistan in 1947. And 1960 alone is often called the Year of Africa: seventeen African countries became independent in that single year.
United Nations member states 1945 — fifty countries signed the Charter in San Francisco 51 Today 193 and the overwhelming majority of that growth is decolonization
One structural feature to know cold. The UN Security Council gives five permanent members a veto over its resolutions — built into the design in 1945. That is why the Council can be decisive on some questions and completely stuck on others, and why arguments about reforming it never quite go away.
🔑Key Terms
🤝AllianceA binding agreement in which countries promise to defend one another. In 1914 Europe’s overlapping alliances converted a regional quarrel into a continental war in about five weeks.
✋ArmisticeA formal agreement to stop fighting while terms are negotiated — a ceasefire, not a peace treaty. 11 November 1918 ended the combat; Versailles set the terms seven months later.
💰ReparationsPayments a defeated country is required to make to the victors as compensation for war damage.
📉DepressionA severe, prolonged collapse in economic activity — production falls, banks fail, unemployment stays high for years. The Great Depression began in 1929 and spread worldwide.
⚠️FascismA political movement built on extreme nationalism, a single all-powerful leader and party, the glorification of force, and the crushing of dissent and minority groups.
🕯️HolocaustThe systematic, state-sponsored persecution and murder of six million European Jews by Nazi Germany and its allies and collaborators, 1933–1945. Roma and Sinti, people with disabilities, Poles, Soviet prisoners of war and others were also targeted.
⚖️GenocideThe deliberate attempt to destroy a national, ethnic, racial or religious group as such. Raphael Lemkin coined the word in 1944; the UN Genocide Convention defined it in international law in 1948.
❄️Cold WarThe rivalry between the United States and the Soviet Union from roughly 1947 to 1991, waged through alliances, nuclear arms races, propaganda, espionage and proxy wars rather than direct combat between the two powers.
🏴DecolonizationThe process by which colonies became independent nations, concentrated in Asia and Africa between 1945 and the mid-1970s.
🌍United NationsFounded in 1945 to prevent war and coordinate cooperation among states. Fifty countries signed the Charter in San Francisco; today the UN has 193 member states.
🌎Where This Shows Up Now
✈️Every international flight and cross-border weather forecast. The International Civil Aviation Organization and the World Meteorological Organization are UN agencies built in the 1940s. Flight corridors, radio frequencies and the weather data feeding your phone’s forecast all depend on countries that frequently disagree still sharing standards through machinery assembled after 1945.
🏛️Courtrooms in The Hague. Before 1945, the idea that a head of state could be put on trial for what his government did to civilians had almost no legal footing. The International Criminal Court, opened in 2002, is a direct descendant of the Nuremberg courtroom — and arguments over its authority, its jurisdiction, and which powerful states accept it are very much live news today.
📜Testimony archives. Survivors spent decades recording interviews — tens of thousands of them, transcribed, archived and indexed — precisely because they understood that the last eyewitness would eventually die while denial would still be in business. Documents, museums and preserved sites do a job no treaty can do alone: they make events difficult to argue away.
📌Remember This
1World War I had a trigger (Sarajevo) and a structure (interlocking alliances, arms buildup, imperial rivalry, aggressive nationalism). Collapsing the two into one is the commonest error about 1914 — the spark only matters because the room was already full of fuel.
2The interwar years are the hinge connecting the two wars: an armistice and treaty that satisfied nobody, an economic collapse that wrecked ordinary households, and fascist movements that offered order and pride in exchange for freedom and truth.
3The century’s answer to its own catastrophes was institutions and memory — the UN, the Genocide Convention, human rights law, archives, testimony, preserved sites. Neither institutions nor memory maintain themselves. Every generation either keeps them running or doesn’t.
🤔 Think about it
The Treaty of Versailles is frequently blamed for causing World War II. But treaties do not cast spells — people make choices. What else would you need to know about Germany between 1919 and 1933 before deciding how much explanatory weight the treaty deserves? What would count as evidence either way?
For forty years both superpowers held enough nuclear weapons to destroy each other, and neither used them. Was that deterrence working as designed, a run of extraordinary luck, or something else entirely? Name one piece of evidence that would push you toward each answer.
⭐ Remember: the trigger explains the timing, the structure explains the size — and institutions and memory are not decorations on this history. They are load-bearing walls, and walls need maintenance.
✏️ ClickClass Stretch Anchor Chart · World History · The Twentieth Century
From ClickClass — hundreds of free printables at clickclassedu.com/printables