World History — World Wars, UN, Cold War, Decolonization, Revolutions

World History questions appear in most PSC exams (2-4 questions). Focus on dates, treaties, key leaders, and outcomes of major events. This is a high-return topic with predictable questions.

Major Revolutions

Revolution	Year	Key Facts
Glorious Revolution	1688	England; James II overthrown; William and Mary; constitutional monarchy established
American Revolution	1775-1783	13 colonies vs Britain; Declaration of Independence (4 July 1776); George Washington — first President
French Revolution	1789-1799	”Liberty, Equality, Fraternity”; Bastille stormed (14 July 1789); Louis XVI executed; Reign of Terror; Napoleon rose to power
Russian Revolution	1917	February Revolution (Tsar Nicholas II abdicated); October Revolution (Bolsheviks under Lenin seized power); led to USSR formation (1922)
Chinese Revolution	1949	Mao Zedong defeated Kuomintang (Chiang Kai-shek); People’s Republic of China established (1 October 1949)
Industrial Revolution	~1760-1840	Started in Britain; steam engine (James Watt); textiles, iron, coal; transformed economies
Cuban Revolution	1953-1959	Fidel Castro overthrew Batista; Cuba became communist

World War I (1914-1918)

Causes

• Immediate cause: Assassination of Archduke Franz Ferdinand of Austria-Hungary in Sarajevo (28 June 1914) by Gavrilo Princip.
• Underlying causes: Militarism, Alliances, Imperialism, Nationalism (MAIN).

Key Alliances

Allied/Entente Powers	Central Powers
Britain, France, Russia	Germany, Austria-Hungary, Ottoman Empire
Italy (joined 1915), USA (joined 1917)	Bulgaria

Key Facts

Fact	Detail
Duration	28 July 1914 — 11 November 1918
USA entered	1917 (Zimmermann Telegram, unrestricted submarine warfare)
Treaty ending WWI	Treaty of Versailles (28 June 1919)
New world body	League of Nations (1920, proposed by Woodrow Wilson)
Casualties	~17 million dead
Empires dissolved	Ottoman, Austro-Hungarian, German, Russian

Treaty of Versailles (1919)

• Germany accepted War Guilt Clause (Article 231).
• Massive reparations imposed on Germany.
• Germany lost Alsace-Lorraine to France.
• League of Nations established (USA did NOT join despite Wilson’s proposal).
• Seeds of World War II were sown.

World War II (1939-1945)

Causes

• Treaty of Versailles humiliation of Germany.
• Rise of fascism (Hitler in Germany, Mussolini in Italy).
• Failure of the League of Nations.
• Policy of appeasement (e.g., Munich Agreement 1938).
• Immediate cause: Germany invaded Poland (1 September 1939).

Key Alliances

Allied Powers	Axis Powers
Britain, France, USSR, USA, China	Germany, Italy, Japan

Key Events Timeline

Year	Event
1939	Germany invades Poland; Britain and France declare war
1940	Fall of France; Battle of Britain; Dunkirk evacuation
1941	Germany invades USSR (Operation Barbarossa); Japan attacks Pearl Harbor (7 Dec) — USA enters war
1942	Battle of Stalingrad begins (turning point in Europe)
1943	Italy surrenders
1944	D-Day (6 June) — Allied invasion of Normandy
1945	Hitler’s suicide (30 April); Germany surrenders (8 May — V-E Day)
1945	Atomic bombs on Hiroshima (6 Aug) and Nagasaki (9 Aug); Japan surrenders (15 Aug — V-J Day)

Key Facts

Fact	Detail
Deadliest conflict	~70-85 million dead
Holocaust	6 million Jews killed by Nazi Germany
Nuremberg Trials	War crimes tribunal (1945-46)
Hiroshima bomb name	”Little Boy” (uranium); Nagasaki: “Fat Man” (plutonium)

United Nations Organization

Formation

• Established: 24 October 1945 (UN Day).
• Charter signed: 26 June 1945, San Francisco.
• Headquarters: New York City.
• Predecessor: League of Nations (dissolved 1946).
• Founding members: 51 countries (India was a founding member).
• Current members: 193 (as of 2026).

Principal Organs

Organ	Key Facts
General Assembly	All 193 members; each has 1 vote; meets annually; “parliament of nations”
Security Council	15 members (5 permanent + 10 non-permanent); maintains international peace
Permanent members (P5)	USA, UK, France, Russia, China — each has veto power
Non-permanent members	Elected for 2-year terms by General Assembly
Secretariat	Administrative body; headed by Secretary-General
ICJ (International Court of Justice)	The Hague, Netherlands; 15 judges; settles disputes between states
ECOSOC	Economic and Social Council; coordinates economic/social work
Trusteeship Council	Suspended operations in 1994 (no more trust territories)

Important UN Agencies

Agency	Full Name	HQ
WHO	World Health Organization	Geneva
UNESCO	UN Educational, Scientific and Cultural Organization	Paris
UNICEF	UN Children’s Fund	New York
ILO	International Labour Organization	Geneva
FAO	Food and Agriculture Organization	Rome
IMF	International Monetary Fund	Washington D.C.
World Bank	International Bank for Reconstruction and Development	Washington D.C.
WTO	World Trade Organization	Geneva

UN Secretaries-General

Name	Country	Term
Trygve Lie	Norway	1946-1952
Dag Hammarskjold	Sweden	1953-1961
U Thant	Myanmar	1961-1971
Kurt Waldheim	Austria	1972-1981
Javier Perez de Cuellar	Peru	1982-1991
Boutros Boutros-Ghali	Egypt	1992-1996
Kofi Annan	Ghana	1997-2006
Ban Ki-moon	South Korea	2007-2016
Antonio Guterres	Portugal	2017-present

Cold War (1947-1991)

Aspect	Detail
What	Ideological/geopolitical rivalry between USA (capitalism) and USSR (communism) — no direct war
Start	After WWII (~1947, Truman Doctrine)
End	Dissolution of USSR (26 December 1991)
Key events	Berlin Blockade (1948), Korean War (1950-53), Cuban Missile Crisis (1962), Vietnam War (1955-75), Berlin Wall fall (1989)
Military alliances	NATO (1949, US-led) vs Warsaw Pact (1955, USSR-led)
Non-Aligned Movement	India, Yugoslavia, Egypt, Indonesia — refused to align (Bandung Conference 1955; NAM founded 1961 in Belgrade)
Space Race	Sputnik (USSR, 1957, first satellite); Apollo 11 (USA, 1969, first moon landing)

Decolonization (Post-1945)

Country	Independence Year	Colonial Power
India	1947	Britain
Indonesia	1945	Netherlands
Vietnam	1945 (declared), 1954 (from France)	France
Ghana	1957	Britain (first sub-Saharan African country)
Algeria	1962	France
Kenya	1963	Britain
South Africa (end of apartheid)	1994	Internal (Nelson Mandela elected)

European Union

Fact	Detail
Precursor	European Coal and Steel Community (1951); EEC/Treaty of Rome (1957)
EU formed	Maastricht Treaty (1993)
Members	27 countries (after Brexit — UK left 31 Jan 2020)
Currency	Euro (used by 20 member states — Eurozone)
HQ	Brussels (Belgium)
European Parliament	Strasbourg (France)
ECB	European Central Bank — Frankfurt (Germany)

Focus on exact dates, treaty names, and the UN structure — these yield the most marks per hour of study.