The precious powerful empire (before Britain) was undoubtedly the Spanish Empire.

The Spanish-American war was closer to the USA opportunistically feasting upon the remains of the fallen empire (The British already overtook the Spanish in terms of power).

It's hard to pinpoint the fall of the Spanish Empire. But it's even harder to point out military action between Spain and Britain (undoubtedly the rising star in the next centuries). There is the big war of Spanish Succession but that's more opportunistic and more like a major civil war that spilled out of Spain and across Europe.

Lots of war between Spain, HRR, France and other parties. But strangely not so much with Britain....

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In both Spanish and British cases, the real enemy the whole time was just a boatload of debt.