War Finance in the 20th Century

Every war is two wars: the one at the front and the one in the treasury. The 20th century’s great powers won and lost both kinds, and most of the financial machinery around you, from the deduction line on your payslip to central-bank independence, was invented to pay for them.

The three ways to pay for a war

Strip away the detail and every war chest fills three ways: tax now, borrow from the future, or print and let inflation collect quietly. Every combatant used all three; the mix decided what the postwar decade looked like, who paid, and whether they ever noticed paying.

July 1914: finance breaks before the armies march

The first battle of World War I happened in the money markets, before the guns. In the last week of July 1914 the world’s financial plumbing, centred on London bills of exchange, simply seized: continental debtors could not remit, London discount houses faced ruin, and the London Stock Exchange closed at the end of July and stayed shut for over five months. Governments responded with moratoria and emergency liquidity, a preview, in miniature, of 2008. The gold standard was suspended in practice everywhere; the century of managed money had begun before the first trench was dug.

1914–1918: the improvised war

Britain taxed hardest: the standard rate of income tax rose roughly fivefold, from around 6% to 30% by the end, with surtaxes above, and still covered only a minority of war spending. America invented mass retail borrowing: four Liberty Loan drives plus a Victory Loan raised over $20 billion from tens of millions of citizens, many buying a security for the first time in their lives, sold with posters, parades and movie stars. The bond drive taught an entire nation what a bond was, a financial-literacy program with artillery in the background.

Germany made the fateful choice: it financed the war overwhelmingly by borrowing at home, nine war-loan drives raising close to 100 billion marks, on the explicit bet that defeated enemies would pay reparations. Germany lost the bet, owed the loans and reparations, and had shut off its tax option politically. Only the printing press remained.

1923: anatomy of a hyperinflation

The end state is famous, by November 1923 one US dollar traded around 4.2 trillion marks, but the mechanism matters more than the zeros. The final spiral had a specific trigger: when France occupied the Ruhr in January 1923, Berlin financed “passive resistance”, paying an entire industrial region to strike, with freshly printed money. Velocity took over: wages paid twice daily and spent within the hour, prices repriced faster than they could be printed, savings and nine patriotic war loans evaporated together. The middle class that had lent Germany its war was expropriated to zero, a political wound that never fully closed.

The stabilization is the nerd’s treasure. In November 1923 Germany introduced the Rentenmark, a currency “backed” by a blanket mortgage on the nation’s land and industry. Nobody could redeem a banknote for a field; the backing was, technically, fiction. But the quantity was credibly capped, the budget was cut, the Ruhr subsidy ended, and the old mark was pegged at one trillion to one. It held within weeks. Money, it turns out, is belief with good stage management, the Rentenmark is the purest demonstration in monetary history. Its guardian’s successor, the Bundesbank of 1957, was built constitutionally paranoid about inflation, and that paranoia, exported, still shapes the European Central Bank you live under today.

Inflation is the one war tax nobody votes for and everybody pays, in 1923 Germany collected it all at once, from exactly the citizens who had lent it the war.

1939–1945: the managed war

The second war was financed with the manual the first had written. Washington broadened the income tax from a rich man’s levy of about four million payers to a mass tax of over forty million, and in 1943 invented payroll withholding so the money arrived continuously, invisibly, before workers ever touched it. The deduction line on your payslip is a World War II artifact that never demobilized. On top: War Bond drives raised on the order of $185 billion, and the Federal Reserve formally pegged Treasury yields, three-eighths of a percent on bills, a 2.5% ceiling on long bonds, making the debt cheap by decree. That peg outlived the war by six years, until the Treasury–Fed Accord of 1951, the founding document of modern central-bank independence. Independence was not granted; it was won back, from war finance.

Britain ran the intellectual version: Keynes’s 1940 pamphlet How to Pay for the War proposed compulsory saving, deferred pay, returned after victory, to fund the fight while throttling wartime inflation; a version was implemented. Britain ended the war around 240% of GDP in debt and dependent on American credit; the final installment on those US loans was paid in December 2006, sixty-one years after the peace. Germany, for its part, financed war by extraction: occupation levies and rigged clearing accounts made conquered Europe pay for its own occupation · France’s tribute alone dwarfed its prewar defense budget. Plunder is the fourth way to pay for a war; it lasts exactly as long as the winning does.

The melt: how the mountain disappeared

The Allies never dramatically repaid the mountain. They dissolved it. Two decades of strong growth plus moderate inflation, with interest rates held politely below both (the peg, then regulation), took US debt from roughly 106% of GDP in 1946 to the low twenties by the mid-1970s. Bondholders were repaid in full, in money worth a fraction of what they had lent: financial repression, war finance’s polite sequel. Korea, by contrast, was substantially tax-financed · Truman pushed taxes up rather than borrow, and produced no comparable inflation surge. Vietnam was the counterexample that broke things: deficits on top of Great Society spending, no early tax rise, inflation accelerating from 1965, a belated surcharge in 1968, and a gold-pegged dollar making the bill visible to every foreign central bank. The 1970s inflation and the end of Bretton Woods were, in a real sense, the delayed invoice of the 1960s.

The war without shooting

The Cold War’s finance decided it. American defense spending peaked near 14% of GDP during Korea and settled toward 5–6% by the 1980s, heavy, but carried by the world’s largest and most flexible economy, funded through deep bond markets at market rates. Western estimates put the Soviet burden at perhaps 15–25% of a much smaller, less efficient economy, sustained for decades, priced by no market at all. One side’s military budget was a line item; the other’s was a tourniquet. Sustainable finance turned out to be a weapons system, the one that fired last.