In his excellent newsletter, Michael Pettis, a finance professor at the Guanghua School of Management, offers a useful intellectual device:
The British were overextended militarily at the end of the 19thCentury and the beginning of the 20th Century, and they subsequently went into decline. And since the US is now militarily overextended, it is obvious, we are told, that the US Empire must be in decline.
The problem with this kind of prediction is that it assumes its conclusions. I am not sure what military overextension means beyond having a very high military budget, commitments in a number of difficult places, and a real struggle ahead.
By that definition, if one didn’t know the subsequent history, one could have easily argued that Great Britain, or its predecessor, was militarily overextended in the early Elizabethan period. One could also easily argue that it was militarily overextended during the Glorious Revolution, that it was militarily overextended prior to the US Revolution, that it was militarily overextended during the Napoleonic period, and so on for a number of periods before the end of the 19th century.
But because those earlier periods in British history took place while the country was still rising, they do not count as periods of military overextension.