In 1914, Japan joined the First World War on the Allied side. It barely fought in Europe.
But the war changed Japan more than almost any other country involved.
Cause and consequence: a war fought far away, felt very close to home: Japan sent a small force to seize German colonies in China and the Pacific. The real story of Japan's war was economic, not military — and that economic story reshaped Japanese society for the next decade.
With Europe's factories turned over to making weapons, European exporters vanished from Asian markets almost overnight.
Japan rushed in to fill the gap.
- Economic boom — Japanese factories supplied the Allies with munitions, ships and textiles, while also selling into markets across Asia that European producers had abandoned.
- Industrial expansion — heavy industry (shipbuilding, chemicals, steel) grew fast; Japan went from a debtor nation to a creditor nation by 1918.
- New markets in Asia — Japanese goods (especially cotton textiles) flooded into China, India and Southeast Asia, regions European firms could no longer supply.
- A new class of the rich — war profiteers ('narikin', literally 'newly rich') built huge fortunes almost overnight, while ordinary workers' wages struggled to keep up with rising prices.
This boom was not evenly shared. Rice prices rose sharply because of wartime demand and speculation.
By 1918, that price rise triggered the huge Rice Riots, with protests across the country — an early sign that Japan's new wealth was creating new tensions.
The Twenty-One Demands, 1915
With the European powers distracted by war, Japan saw an opportunity in China. In January 1915, Japan's government presented the Chinese government with the Twenty-One Demands.
| Group of demands | What Japan wanted |
|---|---|
| Groups 1–2 | Confirm Japanese control of former German territory in Shandong; extend Japan's lease and rights in Manchuria and Inner Mongolia to 99 years |
| Group 3 | Japanese control over a major Chinese mining and iron company |
| Group 4 | China must not give any other coastal territory to a foreign power |
| Group 5 (the most extreme) | Japanese 'advisers' embedded in China's government, police and army — effectively turning China into a Japanese protectorate |
China's government, led by Yuan Shikai, resisted Group 5 fiercely. Japan eventually dropped the harshest parts under pressure, but China still had to accept most of Groups 1–4 in May 1915.
Why this mattered so much: The Twenty-One Demands humiliated China and provoked huge anti-Japanese boycotts and protests, feeding directly into the nationalism that exploded in the May Fourth Movement. For Japan, they showed the government was willing to use the war as cover to expand aggressively into China — a pattern of behaviour that would recur in the 1930s.
So the same war that brought Japan riches also brought Japan a taste for using its growing power to push other Asian nations around. Both things were happening at once.
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By 1919, Japan sat at the table with the world's great powers at the Paris Peace Conference. That alone was a huge change from a few decades earlier, when Japan had been forced to accept unequal treaties from the West.
- A seat among the 'Big Five' — Japan was one of the five main powers at Versailles alongside Britain, France, the USA and Italy, a mark of real international status.
- Keeping Shandong — Japan was allowed to keep the former German rights in Shandong, over furious Chinese objections.
- Pacific island mandates — Japan received League of Nations mandates over former German islands north of the equator (the Marshalls, Carolines, Marianas).
- Founding member of the League of Nations — Japan became a permanent member of the League's governing Council, confirming its place as a recognised great power.
Japan also tried to get something symbolic but important written into the League's founding Covenant: a racial equality clause, declaring that all League members should be treated equally regardless of race.
The racial equality clause was rejected: A majority of delegates actually voted in favour. But the conference chair — US President Woodrow Wilson — ruled that it needed unanimous support and let it fail.
Who blocked it, and how Japan reacted
- Australia and Britain led the opposition, worried about immigration policy.
- Many in Japan saw this as proof that the Western powers still did not treat Japan as a true equal, whatever the seat at the table suggested.
This is a genuine historical debate worth holding in your head for the essay: did WWI make Japan a fully accepted great power, or just a power tolerated on Western terms?
Japan had truly arrived as a great power
- Permanent seat on the League Council — a status no other Asian nation held
- Territorial gains (Shandong, Pacific mandates) recognised by treaty
- Economic transformation from debtor to creditor nation during the war
- Naval power confirmed at the 1921–22 Washington Conference, ranked among the top three navies
Japan's rise was still limited and resented
- The racial equality clause Japan proposed was rejected at Versailles, a sign it was not treated as a true equal.
- The Washington Conference fixed Japan's navy below Britain's and the USA's (a 5:5:3 ratio), which many Japanese resented.
- Japan was pressured to hand Shandong back to China in 1922, limiting its wartime gains.
- Western immigration barriers (such as the US 1924 Immigration Act excluding Japanese) showed lingering racial prejudice.
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The years roughly from 1912 to 1926 are called the Taishō era. This period saw Japan's most serious experiment with party-led, more democratic politics before the Second World War.
Party cabinets emerge
From 1918, Japan was governed for the first time by cabinets led by the head of the largest party in the Diet (parliament), not by unelected genrō (elder statesmen) or military men. Hara Takashi became the first commoner and first party-based prime minister in 1918.
1925: universal male suffrage
The General Election Law of 1925 gave the vote to all men aged 25+, regardless of how much tax they paid — expanding the electorate roughly fourfold, from about 3 million to around 12.5 million voters.
1925: the Peace Preservation Law — passed the SAME YEAR
Alongside suffrage, the government passed a law banning any group that wanted to change the 'kokutai' (the imperial political system) or abolish private property — aimed squarely at socialists, communists and radical unions.
1925 gave with one hand (the vote) and took with the other (the right to organise against the system).
This pairing IS the essay: Almost every Paper 3 essay on Taishō Japan turns on this exact tension: was 1925 a genuine democratic breakthrough, or did the Peace Preservation Law prove the whole thing was tightly controlled 'democracy' that never threatened the emperor system or the establishment? Learn both laws together, not separately.
Women, notably, still could not vote at all — despite active campaigning by groups like the New Women's Association, led by figures such as Ichikawa Fusae. So 'universal' suffrage in 1925 meant universal for men only.
Social change and unrest
Taishō Japan was also a period of real social change beneath the politics. Cities grew fast, and a new urban culture appeared — the 'moga' (modern girl) and 'mobo' (modern boy), Western fashion, jazz, cinema and department stores.
- Labour unrest — industrial workers, whose numbers had grown hugely during the WWI boom, organised strikes in growing numbers through the early 1920s as unions formed despite legal restrictions.
- Tenant farmer disputes — in the countryside, tenant farmers increasingly organised against high rents charged by landlords, another sign of rising social pressure.
- Rice Riots of 1918 — the wartime price spike triggered protests involving over a million people across Japan, showing ordinary people's frustration with inequality.
- Growing left-wing movements — socialist and (from 1922) communist organising grew, which is exactly what the Peace Preservation Law was designed to suppress.
The Great Kantō earthquake, 1923
On 1 September 1923, a massive earthquake struck the Tokyo–Yokohama region. It killed over 100,000 people, mostly in the firestorms that followed, and destroyed huge parts of both cities.
The disaster's darkest consequence: In the chaos, false rumours spread that Korean residents were poisoning wells and starting fires. Vigilante groups, sometimes helped by police and soldiers, murdered several thousand Korean residents (and some Chinese and Japanese leftists) in the days after the quake.
Why it matters: It was one of the ugliest episodes of the whole era. It is a stark reminder of ethnic tension and the fragility of order, even during 'democratic' Taishō.
The earthquake also had a big economic cost: rebuilding Tokyo drained government funds and left banks holding large amounts of bad debt from earthquake-damaged businesses, weakening the economy well before 1929.
The Great Depression from 1929
The Wall Street Crash of October 1929 hit Japan especially hard because its economy depended heavily on exports, above all silk to the United States.
- Silk collapsed — American demand for silk stockings and textiles collapsed, devastating rural Japan since millions of farming families relied on silkworm cultivation for cash income.
- Rural crisis — falling farm prices meant many families could not survive; there are documented cases of families selling daughters into indentured work or prostitution to survive, a shocking measure of rural desperation.
- Unemployment and wage cuts — urban factories laid off workers and cut wages as exports and demand collapsed, adding urban misery to rural crisis.
- Political fallout — the Depression discredited party-cabinet politicians (seen as tied to big business 'zaibatsu' conglomerates) and strengthened the argument, pushed by the military and ultranationalists, that only strong, disciplined leadership — not party squabbling — could save Japan.
This economic collapse is the hinge between this micro and what comes next: it is the crisis that helped the military and radical nationalists discredit party democracy and push Japan toward the more aggressive, militarist path of the 1930s.