At the beginning of the twentieth century, the British Empire was the biggest global superpower. The British became a superpower during this time due to colonial rule. From colonisation they gained economically from the cheap raw materials. Maintaining colonial rule depended on military power. But when Britain started to decolonise its Empires they lost the title of a superpower. This was due to : economic decline, Britain had overspent on war efforts and after WW2 was showing serious signs of economic ‘slowdown’. Also loss of military influence after the war. Moreover many colonies fought for the allies with their own independent armies. One by one after the war, for a range of reasons most of the colonies became indepent. So with this example we can see that the cause of power to shift was due to the war and the economic pressure it put on the British to lose its superpower statues.
So we can see from British Empire, that was once a giant empire with vast areas of huge armies and thriving economies. However they lost their power of being a superpower due to economic problems and war. We can already see that economics and military have a large impact towards maintaining superpower. Military helps them keep control of their power against uprising and economic helps them pay for the military. So when Britain become in debt due to ww2 it lost all its power.
By 1900, the USA had taken over from Britain as the worlds largest economy. By 1940, it was the worlds largest manufacturer of industrial and consumer good. Also the US military dominates global arms and defence spending. We can see how power had shifted between Britain now to the US