World Wars I & II — the century's two earthquakes

When Archduke Franz Ferdinand of Austria-Hungary stepped off a train in Sarajevo on the morning of 28 June 1914, the world he knew — of empires, gold standards and steady progress — had less than six hours to live. By sundown he was dead at the hands of Gavrilo Princip, a 19-year-old Bosnian-Serb nationalist, and within five weeks every Great Power had been pulled into the largest war humanity had yet seen. Thirty-one years later, on 15 August 1945, the second war it spawned ended over the radioactive ruins of two Japanese cities.

For UPSC, the World Wars are not optional. They explain the rise of the USSR and USA as superpowers, the collapse of European empires, the birth of the United Nations, the Bretton Woods financial order, the partition of Palestine and Korea — and, most importantly for Indian aspirants, the final acceleration of India's freedom struggle.

World War I — the MAIN causes

Historians use the mnemonic MAIN to summarise the long-term causes of the first war: Militarism, Alliances, Imperialism and Nationalism. Each had been building for decades; the assassination at Sarajevo simply lit the fuse.

Militarism

Between 1900 and 1914 European armies doubled in size. Britain and Germany ran a naval arms race centred on the Dreadnought battleship (Britain launched HMS Dreadnought in 1906; Germany responded with its own). Conscription was universal on the continent; war was glamorised in newspapers and school textbooks.

Alliances

Two armed blocs faced each other. The Triple Alliance (1882) linked Germany, Austria-Hungary and Italy. The Triple Entente (1907) linked Britain, France and Russia. Any local quarrel could now drag in all six.

Imperialism

The Scramble for Africa (1881-1914) and rivalries in China, Persia and the Ottoman Empire had created sharp tensions. Germany, late to the colonial table, demanded a "place in the sun" that Britain and France were unwilling to grant.

Nationalism

Pan-Slavism in the Balkans threatened the multi-ethnic Austro-Hungarian and Ottoman empires. Serbia's expansionist ambitions after the Balkan Wars (1912-13) frightened Vienna. Within the German Empire, Bismarckian nationalism had hardened into Wilhelm II's aggressive Weltpolitik.

WWI — course of the war

The Schlieffen Plan — Germany's blueprint for a quick knock-out blow against France — failed at the First Battle of the Marne (Sep 1914). The Western Front then froze into 700 km of trenches stretching from the English Channel to Switzerland, where industrial weapons (machine guns, poison gas first used at Ypres in April 1915, tanks at the Somme in 1916) made attack suicidal.

Two events in 1917 changed everything. In April the United States entered the war on the Entente side after Germany resumed unrestricted submarine warfare and the Zimmermann telegram revealed a German plot to incite Mexico against America. In October the Bolshevik Revolution took Russia out of the war (Treaty of Brest-Litovsk, March 1918) and gave the world its first communist state — a development whose shockwaves shaped the rest of the 20th century.

Exhausted and starving from the Allied naval blockade, Germany finally accepted the Armistice on the eleventh hour of the eleventh day of the eleventh month — 11 November 1918, observed since as Armistice Day.

Treaty of Versailles & the League of Nations

The peace conference convened at Versailles in January 1919, dominated by the "Big Four" — Woodrow Wilson (USA), David Lloyd George (UK), Georges Clemenceau (France) and Vittorio Orlando (Italy). Germany was not invited to negotiate.

The Treaty of Versailles was signed on 28 June 1919 — five years to the day after Sarajevo — in the Hall of Mirrors at the Palace of Versailles. Its punitive terms shaped the next two decades:

• War Guilt Clause (Article 231) — sole German responsibility for the war.
• Reparations — 132 billion gold marks (~$33 billion).
• Territorial losses — 13% of Germany, all overseas colonies; Alsace-Lorraine returned to France; Polish Corridor created.
• Military limits — army capped at 100,000; no tanks, submarines or air force; Rhineland demilitarised.
• League of Nations — established under Wilson's 14 Points; headquartered in Geneva from January 1920.

The League of Nations was the first global organisation to maintain peace through collective security. It had real successes — settling the Aaland Islands dispute (1921), supervising the Saar plebiscite (1935), running the ILO and the Permanent Court of International Justice. But its weaknesses were fatal: the US Senate, in a fit of isolationism, refused to ratify the Treaty and never joined; the USSR was admitted only in 1934 and expelled in 1939; Germany joined in 1926 and left in 1933 under Hitler; and the League had no military force to enforce its decisions. It failed every major test of the 1930s — Japan's invasion of Manchuria (1931), Italy's invasion of Abyssinia (1935), Germany's remilitarisation of the Rhineland (1936).

The interwar years — a 20-year truce

Marshal Foch, on hearing the Versailles terms, supposedly said: "This is not peace. It is an armistice for twenty years." He was off by 65 days. Three forces made WWII inevitable:

• Economic chaos — German hyperinflation (1923, when a loaf of bread cost 200 billion marks); the Wall Street Crash (Oct 1929) triggered the Great Depression, German unemployment hit 6 million by 1932.
• Rise of dictatorships — Mussolini's Fascists took Rome (1922); Hitler's NSDAP won 37% in July 1932, he became Chancellor on 30 January 1933 and Führer on Hindenburg's death (Aug 1934); Stalin consolidated power in the USSR; militarists ruled Japan from 1931.
• Failure of appeasement — Britain and France conceded territory after territory: Rhineland (1936), Anschluss with Austria (March 1938), Sudetenland under the Munich Agreement (29-30 September 1938) — Chamberlain's "peace for our time" — and finally the rump of Czechoslovakia (March 1939).

"You were given the choice between war and dishonour. You chose dishonour and you will have war."
— Winston Churchill to Neville Chamberlain after Munich, 1938

On 23 August 1939 the world was stunned by the Molotov-Ribbentrop Pact: a non-aggression treaty between Nazi Germany and Soviet Russia with secret protocols dividing Poland and the Baltic states. Nine days later, on 1 September 1939, Hitler invaded Poland. Britain and France declared war on 3 September.

WWII — causes

While the World Wars are sometimes treated as one long conflict with a long interval, the immediate causes of WWII deserve separate listing for UPSC:

1. Treaty of Versailles's harshness — provided ideological fuel for Nazi revisionism.
2. Great Depression — destroyed faith in liberal democracy and capitalism, opened space for totalitarianism.
3. Failure of the League of Nations — collective security proved a paper tiger.
4. Rise of Fascism & Nazism — explicit, militarised expansionism.
5. Policy of Appeasement — Anglo-French weakness encouraged Hitler.
6. Japanese militarism & the Greater East Asia Co-Prosperity Sphere — Manchuria 1931, China 1937.
7. Molotov-Ribbentrop Pact — green-lit invasion of Poland.

WWII — course of the war

Unlike the static WWI, the Second World War was a war of movement on six continents and across all oceans.

Three turning points decided the war. Battle of Britain (July-October 1940) — the RAF, helped by radar and the Spitfire, denied Hitler the air superiority he needed for Operation Sea Lion (invasion of Britain). Pearl Harbor (7 December 1941) — Japan's surprise attack on the US Pacific Fleet killed 2,400 Americans and brought the United States into the war ("a date which will live in infamy" — FDR). Battle of Stalingrad (August 1942 - February 1943) — the Red Army's encirclement of Field Marshal Paulus's Sixth Army killed or captured 850,000 Axis troops and broke the back of the Wehrmacht.

D-Day, 6 June 1944, opened the long-awaited second front. 156,000 Allied troops landed on five Normandy beaches (Utah, Omaha, Gold, Juno, Sword) in the largest amphibious operation in history. Paris was liberated on 25 August. On the Eastern Front the Red Army drove relentlessly westward; Berlin fell on 2 May 1945, Hitler having committed suicide in his bunker on 30 April. Germany's unconditional surrender was signed on 7 May; V-E Day was celebrated on 8 May 1945.

The Holocaust

The Holocaust shaped the post-war moral order. The Nuremberg Trials (1945-46) established the principles of crimes against humanity and individual criminal responsibility — foundations of modern international criminal law. The Universal Declaration of Human Rights (10 December 1948) was a direct response, drafted under Eleanor Roosevelt. The Genocide Convention (1948), the Refugee Convention (1951) and ultimately the creation of Israel (14 May 1948) all flowed from Holocaust memory.

Hiroshima & Nagasaki — the atomic age begins

The Manhattan Project, launched in 1942 under the scientific direction of Robert Oppenheimer at Los Alamos, produced the world's first atomic bomb. The Trinity test on 16 July 1945 in New Mexico proved the design worked. President Truman, having succeeded the late FDR in April 1945, authorised its use against Japan.

• 6 August 1945, 8:15 am — B-29 bomber Enola Gay dropped "Little Boy" (uranium-235 gun-type bomb, ~15 kilotons) on Hiroshima. ~80,000 killed instantly; ~140,000 dead by year-end from blast, burns and radiation.
• 9 August 1945, 11:02 am — "Fat Man" (plutonium implosion bomb, ~21 kilotons) dropped on Nagasaki. ~40,000 killed instantly; ~70,000 by year-end.
• 15 August 1945 — Emperor Hirohito's radio broadcast announced Japan's surrender (V-J Day); formal surrender signed aboard the USS Missouri in Tokyo Bay on 2 September 1945.

The historical and ethical debates remain open. Defenders argue the bombs avoided a costly invasion of Japan (Operation Downfall, projected to cost ~500,000 Allied lives) and accelerated surrender. Critics note Japan was already collapsing, that Nagasaki in particular was militarily questionable, and that civilian targeting violated just-war principles. What is undisputed is that the bombs ushered in the nuclear age: the Cold War arms race, the IAEA (1957), the Partial Test Ban Treaty (1963), the Non-Proliferation Treaty (1968), and the constant, unresolved question of how humanity lives with weapons that can destroy it.

UN and the post-war order

The Allies had begun planning the post-war world while bullets still flew. The Atlantic Charter (Aug 1941, Roosevelt-Churchill), the Tehran Conference (Nov 1943), the Bretton Woods Conference (July 1944 — IMF and World Bank), Dumbarton Oaks (Aug-Oct 1944 — drafting the UN), Yalta (Feb 1945 — spheres of influence) and Potsdam (July-August 1945) collectively created the architecture of the modern international system.

The United Nations was formally established on 24 October 1945 when the UN Charter — drafted at the San Francisco Conference (April-June 1945) and signed by 50 states — was ratified by the five permanent Security Council members. India was a founding member, having signed at San Francisco while still under British rule. The UN replaced the League of Nations and added enforcement teeth (Chapter VII), specialised agencies (WHO, UNESCO, FAO, ILO), and the principle of universal human rights.

The war also bequeathed the Cold War (1947-91) — a 44-year ideological and geopolitical contest between the United States and the Soviet Union that shaped decolonisation, India's Non-Aligned Movement, the Korean War, the Cuban Missile Crisis and ultimately the collapse of the USSR in 1991.

Impact on India — wars that won independence

Both wars were turning points in India's freedom struggle, each in a different way.

World War I and India

India contributed enormously: ~1.3 million soldiers on the Western Front, Mesopotamia, East Africa and Gallipoli. Around 74,000 died and 11 Indians won the Victoria Cross. India also provided £146 million in war loans plus huge quantities of food, leather and jute. Britain promised, through the Montagu Declaration of 20 August 1917, the "progressive realisation of responsible government" in return.

The post-war reality was different. The Rowlatt Act (March 1919) extended wartime emergency powers in peacetime, triggering Gandhi's first all-India satyagraha. The Jallianwala Bagh massacre (13 April 1919) — 379 to 1,000 Indians shot dead by General Dyer's troops — radicalised Indian politics. The Montagu-Chelmsford Reforms / Government of India Act 1919 introduced dyarchy in the provinces but disappointed almost everyone. The wartime experience also produced the Khilafat Movement (1919-22, protesting Versailles's treatment of the Ottoman Caliph) and the Non-Cooperation Movement (1920-22).

World War II and India

Britain dragged India into the war without consulting Indian leaders. Congress provincial ministries resigned in protest in October 1939. Yet India's contribution was again colossal: ~2.5 million Indians volunteered — the largest volunteer army in history — fighting in North Africa (El Alamein), Italy (Monte Cassino), Burma (Kohima-Imphal, 1944) and elsewhere. Around 87,000 died. The Battle of Kohima-Imphal (March-July 1944), voted "Britain's Greatest Battle" by the National Army Museum, stopped the Japanese invasion of India.

Other wartime developments were decisive: the Bengal Famine of 1943 killed ~3 million Indians, largely due to Churchill's wartime grain export priorities and refusal of relief shipments; the Cripps Mission (March 1942) offered dominion status after the war but was rejected (Gandhi: "a post-dated cheque on a failing bank"); the Royal Indian Navy mutiny (February 1946) in Bombay made it clear Britain could no longer rely on Indian armed forces.

The war bankrupted Britain (national debt rose from £760m to £3.5bn), Labour won the 1945 election promising decolonisation, the Cabinet Mission (March 1946) and Mountbatten Plan (June 1947) followed, and India became independent on 15 August 1947. The World Wars did not give India independence — Indian nationalism did — but they decisively shortened the timetable and the Empire's resources for resistance.

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