The second challenge came from the United States, which also was industrializing at a dramatic pace -- a process ironically underwritten by investors from Britain seeking higher returns than they could get at home. The U.S. industrial base created a navy that surpassed the British navy in size early in the 20th century. The window of opportunity that had opened with the defeat of Napoleon was closing as Germany and the United States pressed Britain, even if in an uncoordinated fashion.

The German challenge culminated in World War I, a catastrophe for Britain and for the rest of Europe. Apart from decimating a generation of men, the cost of the war undermined Britain's economic base, subtly shifting London's relationship with its empire. Moreover, British power no longer seemed inevitable, raising the question among those who had not benefitted from British imperialism as to whether the empire could be broken. Britain became more dependent on its empire, somewhat shifting the mutuality of relations. And the cost of policing the empire became prohibitive relative to the benefits. Additionally, the United States was emerging as a potential alternative partner for the components of the empire -- and the German question was not closed.

World War II, the second round of the German war, broke Britain's power. Britain lost the war not to Germany but to the United States. It might have been a benign defeat in the sense that the United States, pursuing its own interests, saved Britain from being forced into an accommodation with Germany. Nevertheless, the balance of power between the United States and Britain completely shifted during the war. Britain emerged from the war vastly weaker economically and militarily than the United States. Though it retained its empire, its ability to hold it depended on the United States. Britain no longer could hold it unilaterally.

British strategy at the end of the war was to remain aligned with the United States and try to find a foundation for the United States to underwrite the retention of the empire. But the United States had no interest in this. It saw its primary strategic interest as blocking the Soviet Union in what became known as the Cold War. Washington saw the empire as undermining this effort, both fueling anti-Western sentiment and perpetuating an economic bloc that had ceased to be self-sustaining.

From Suez to Special Relationship

The U.S. political intervention against the British, French and Israeli attack on Egypt in 1956, which was designed to maintain British control of the Suez Canal, marked the empire's breaking point. Thereafter, the British retreated strategically and psychologically from the empire. They tried to maintain some semblance of enhanced ties with their former colonies through the Commonwealth, but essentially they withdrew to the British Isles.

As it did during World War II, Britain recognized U.S. economic and military primacy, and it recognized it no longer could retain their empire. As an alternative, the British aligned themselves with the U.S.-dominated alliance system and the postwar financial arrangements lumped together under the Bretton Woods system. The British, however, added a dimension to this. Unable to match the United States militarily, they outstripped other American allies both in the quantity of their military resources and in their willingness to use them at the behest of the Americans.

We might call this the "lieutenant strategy." Britain could not be America's equal. However, it could in effect be America's lieutenant, wielding a military force that outstripped in number -- and technical sophistication -- the forces deployed by other European countries. The British maintained a "full-spectrum" military force, smaller than the U.S. military but more capable across the board than militaries of other U.S. allies.