For two centuries an Island twenty miles off the European mainland had acquired an empire spanning every continent.
By 1900, it encompassed modern-day India, Pakistan, Burma, Malaysia, Singapore, Australia, New Zealand and Canada, along with much of the African Continent.
It exerted a strong influence, sometimes equivalent to de facto control, over Latin America, the Persian Gulf, and Egypt.
The birthplace of the Industrial Revolution, Britain had become the “workshop of the world,” and by 1880 it accounted for almost a quarter of the world’s manufacturing output and trade.
Its investments powered global growth, and its fleets protected global trade. Niall Ferguson explained, Britain was “both policeman and banker to the world . . . the first true superpower.”
Britain thus saw itself, and expected others to see it, as number one.
But there were alarming signs by the end of the 19th century that Britain was declining relative to other powers.
In 1899, war with the Boers (descendants of Dutch settlers in what is today South Africa) broke out. Britain had not fought a well-trained adversary with modern weapons for a half century.
The numerically inferior but determined Boers inflicted a series of humiliating defeats on their more powerful enemies.
As he had done earlier in India and Sudan, Churchill rushed to join the fight, only to be captured by the Boers.
The world’s newspapers followed the tale of his subsequent escape and flight to freedom.
Britain eventually won the war, but at immense cost, shaking its imperial reputation.
The German general staff studied the Boer War carefully, concluding, as Paul Kennedy puts it, that “Britain would find it impossible to defend India against a Russian assault,” and “without a total reorganization of its military system, the empire itself would be dissolved within two decades.”
Meanwhile, a host of rivals were chipping away at the substantial head start in science and industry that had cemented Britain’s number-one position following its hard-fought victory over Napoleonic France in 1815.
After the American Civil War and Bismarck’s success in unifying Germany in 1871, Britain watched others adopt its technologies, grow their economies faster, and emerge as peer competitors.
London worried about four rivals in particular: Russia, France, the United States, and Germany.
With the biggest army in Europe, its third-greatest fleet, a rapidly growing industrial base, and the largest landmass of any nation, Russia cast quite a shadow.
New railways enabled Moscow to project power farther and faster than ever before, while its continuous expansion moved its borders steadily closer to British spheres of influence in central, western, and southern Asia.
Despite its weak industrial base, France was an imperial competitor—indeed, the world’s second-largest empire. Colonial disputes led to frequent friction with London and occasional war scares. In 1898, France was forced to back down from a confrontation over Fashoda (in the modern state of South Sudan) when it realized it had no chance of winning a naval conflict.
But maintaining the Two-Power Standard to match the combined power of the …