Mass Atrocities
After 1900

Examining genocide, ethnic cleansing, and state-sponsored violence in the twentieth and twenty-first centuries: causes, patterns, and global responses.

AP World History

Defining Mass Atrocities

Genocide

The deliberate, systematic destruction of a racial, ethnic, religious, or national group, as defined by the 1948 UN Convention.

Ethnic Cleansing

The forced removal of an ethnic or religious group from a territory through violence, deportation, or intimidation.

Crimes Against Humanity

Widespread or systematic attacks against civilian populations, including murder, enslavement, torture, and persecution.

Why the 20th Century?

The twentieth century saw mass atrocities on an unprecedented scale. Several structural forces converged to make large-scale violence both possible and, in some cases, state policy:

1

Modern state power: Centralized bureaucracies, standing armies, and surveillance technologies gave governments the capacity to target entire populations.

2

Nationalist ideologies: Ethno-nationalist movements defined citizenship in exclusionary terms, casting minorities as threats to the nation.

3

Total war and dehumanization: World Wars normalized mass killing and propaganda that portrayed enemy groups as subhuman.

4

Colonial legacies: Imperial divide-and-rule policies deepened ethnic rivalries that later erupted in post-colonial violence.

Timeline: Major Atrocities

1915

Armenian Genocide

Ottoman Empire systematically killed 1-1.5 million Armenians

1932-33

Holodomor

Soviet engineered famine in Ukraine killed 3.5-7.5 million

1941-45

The Holocaust

Nazi Germany murdered 6 million Jews and millions of others

1975-79

Cambodian Genocide

Khmer Rouge killed 1.5-2 million through execution and forced labor

1994

Rwandan Genocide

Approximately 800,000 Tutsi and moderate Hutu killed in 100 days

1995

Srebrenica Massacre

Bosnian Serb forces murdered over 8,000 Bosniak men and boys

The Armenian Genocide (1915-1923)

The Ottoman government, led by the Committee of Union and Progress (the "Young Turks"), orchestrated the deportation and murder of the Armenian minority during World War I. It is widely considered the first modern genocide.

Methods

Death marches into the Syrian desert, mass executions, starvation, and forced labor camps.

Context

WWI provided cover. Armenians were scapegoated as disloyal Christians allied with Russia.

The Holocaust (1941-1945)

Nazi Germany's systematic, state-organized persecution and murder of six million Jews, along with Roma, disabled persons, political opponents, and others. The Holocaust represents the most industrialized genocide in history.

1

Identification: Nuremberg Laws (1935) stripped Jews of citizenship and rights, forcing them to wear yellow stars.

2

Concentration: Ghettos confined Jewish populations in cramped, unsanitary conditions. Over 1,000 ghettos were established.

3

Extermination: The "Final Solution" (1942) created death camps: Auschwitz-Birkenau, Treblinka, Sobibor, and others with gas chambers.

Stanton's Ten Stages of Genocide

Genocide vs. Ethnic Cleansing

	Genocide	Ethnic Cleansing
Primary Intent	Destroy the group	Remove the group
Legal Status	Crime under 1948 Convention	Not separately codified in treaty law
Methods	Mass killing, forced sterilization, starvation	Deportation, intimidation, destruction of property
Overlap	Often occur together: ethnic cleansing can escalate into genocide
Example	Holocaust, Rwanda	Bosnian War, Rohingya crisis

Cambodia: Ideology and Terror

The Khmer Rouge, led by Pol Pot, seized power in 1975 and attempted to create an agrarian communist utopia. The result: 1.5 to 2 million deaths in under four years, roughly 25% of Cambodia's population.

Forced Evacuation

Cities emptied overnight. Phnom Penh's 2 million residents marched into the countryside.

Killing Fields

Execution sites where perceived enemies: intellectuals, minorities, and former officials were murdered.

Rwanda: 100 Days of Horror

In April 1994, extremist Hutu leaders launched a systematic campaign to exterminate the Tutsi minority. Approximately 800,000 people were killed in just 100 days, primarily with machetes and small arms.

1

Colonial roots: Belgian colonizers had hardened Hutu-Tutsi divisions by issuing ethnic identity cards and favoring Tutsis.

2

Radio propaganda: Radio Télévision Libre des Mille Collines broadcast dehumanizing rhetoric, calling Tutsis "cockroaches."

3

International failure: The UN reduced its peacekeeping force as the killing began. The US and European nations refused to intervene.

Bosnia: Srebrenica and the Yugoslav Wars

The breakup of Yugoslavia in the 1990s led to a series of ethnic conflicts. In Bosnia-Herzegovina, Bosnian Serb forces carried out ethnic cleansing against Bosniak Muslims, culminating in the Srebrenica massacre of July 1995.

Siege of Sarajevo

The longest siege in modern warfare (1992-1996). Snipers and shelling targeted civilians for nearly four years.

Srebrenica

Despite being a UN "safe area," over 8,000 Bosniak men and boys were executed by Bosnian Serb forces under Ratko Mladić.

Recurring Patterns and Causes

How to Analyze a Mass Atrocity

1

Identify the context: What political system, economic conditions, and social tensions existed? Was there war or state collapse?

2

Trace the stages: Apply Stanton's model. Where did classification, dehumanization, and organization appear? What role did propaganda play?

3

Examine the perpetrators: Were state actors, paramilitaries, or civilians involved? How were ordinary people mobilized?

4

Assess the international response: Did the UN, regional organizations, or foreign states intervene, ignore, or enable the violence?

5

Evaluate long-term consequences: How did survivors, tribunals, and memory shape post-atrocity societies? Was there denial or reconciliation?

Darfur and 21st-Century Atrocities

Beginning in 2003, the Sudanese government and allied Janjaweed militias targeted non-Arab populations in the Darfur region. The International Criminal Court issued an arrest warrant for President Omar al-Bashir for genocide in 2009: the first sitting head of state charged with genocide.

Darfur (2003-)

300,000+ killed, 2.5 million displaced. Scorched-earth campaigns against villages.

Rohingya (2017)

Myanmar military's "clearance operations" killed thousands and displaced 700,000+ Rohingya to Bangladesh.

Uyghurs (2017-)

China's mass detention of Uyghur Muslims in Xinjiang: forced labor, cultural erasure, and surveillance.

International Responses and Institutions

1

Nuremberg Trials (1945-46): First international war crimes tribunal. Established the principle that individuals, including heads of state, can be held accountable.

2

UN Genocide Convention (1948): Defined genocide in international law and obligated signatories to prevent and punish it.

3

Ad Hoc Tribunals: ICTY (Yugoslavia) and ICTR (Rwanda) prosecuted perpetrators in the 1990s-2000s.

4

International Criminal Court (2002): Permanent court in The Hague to prosecute genocide, war crimes, and crimes against humanity.

5

Responsibility to Protect (R2P, 2005): UN doctrine stating the international community has a duty to intervene when a state fails to protect its people.

Common Mistakes on the AP Exam

✕ Conflating Genocide and War

Genocide is the deliberate targeting of a specific group for destruction: it is not simply "a lot of killing in a war." Civilian casualties in war are not automatically genocide.

✕ Ignoring Intent

The legal definition of genocide requires specific intent (dolus specialis) to destroy a group. Without proven intent, the crime may be classified differently.

✕ Treating All Cases Alike

Each atrocity has unique causes and context. Avoid applying a single template: the Holocaust was industrial, Rwanda was communal, Cambodia was ideological.

Question 1 of 5

Which of the following best describes the legal distinction between genocide and ethnic cleansing?

The critical legal distinction is intent. Genocide requires demonstrable intent to destroy a group "in whole or in part," while ethnic cleansing focuses on forced removal from a territory.

Question 2 of 5

Which colonial legacy most directly contributed to the conditions for the 1994 Rwandan Genocide?

Belgian colonial administrators hardened fluid Hutu-Tutsi distinctions into rigid racial categories, issuing ethnic identity cards and privileging Tutsis. This institutionalized division became the foundation for post-colonial ethnic violence.

Question 3 of 5

In Gregory Stanton's model, "Denial" is classified as which stage of genocide?

Denial is the final stage (Stage 10) in Stanton's model. Perpetrators deny the crime, destroy evidence, and intimidate witnesses. Stanton emphasizes that denial is a reliable predictor of future genocides.

Question 4 of 5

Source: "We have been informed that genocide is being committed in Rwanda. However, the deployment of additional peacekeeping forces is not recommended at this time. The mandate of UNAMIR should be adjusted to focus on negotiating a ceasefire between the parties."

: Adapted from internal UN communications, April 1994

▼ Tap to read passage

This passage best illustrates which failure of the international community during the Rwandan Genocide?

The passage shows that the UN was aware genocide was occurring but chose to reduce rather than strengthen its presence. This reflects the broader failure of political will: governments avoided the term "genocide" to evade the legal obligation to act under the 1948 Convention.

Question 5 of 5

The Cambodian Genocide under the Khmer Rouge most significantly challenges the 1948 UN Genocide Convention because:

The 1948 Convention protects national, ethnic, racial, and religious groups but deliberately excludes political and social groups: a compromise driven by Soviet objections. Since the Khmer Rouge primarily targeted perceived political enemies, intellectuals, and urban dwellers, prosecution under the Convention's strict definition was complicated.

Mass AtrocitiesAfter 1900

Defining Mass Atrocities

Why the 20th Century?

Timeline: Major Atrocities

The Armenian Genocide (1915-1923)

The Holocaust (1941-1945)

Stanton's Ten Stages of Genocide

Genocide vs. Ethnic Cleansing

Cambodia: Ideology and Terror

Rwanda: 100 Days of Horror

Bosnia: Srebrenica and the Yugoslav Wars

Recurring Patterns and Causes

How to Analyze a Mass Atrocity

Darfur and 21st-Century Atrocities

International Responses and Institutions

Common Mistakes on the AP Exam

Question 1 of 5

Question 2 of 5

Question 3 of 5

Question 4 of 5

Question 5 of 5

Mass Atrocities
After 1900