slavery?

The American humorist Will Rogers once exclaimed, with tongue in cheek, though perhaps with a modicum of sobriety, "Thank God we don't get all the government we pay for!"
When it comes to national defense, I'm not sure if Roger's sentiment should make us laugh or cry.
It was said during the Victorian era that the sun never set on the British Empire. They enjoyed political and military hegemony for a time--as had all the other world powers that preceeded them--but their citizenry eventually grew weary of the costly sina qua non imposed by the requirements of, shall we say, noblesse oblige. The prerogatives of empire ultimately became so expensive that it busted the public treasury.
While it's true that America has not pursued colonial ambitions of the sort that have marked--and curtailed--the reign of European powers, this same ignomineous fate is bound to knock on our door.
Interestingly, modern day America shares certain attributes with the Roman Empire that would likely impart greater longevity to a civilization. For example, the genius of the Roman Empire--and the reason it survived so long--was that it successfully grafted those it conquered into it's increasingly diverse cultural mileau. When Rome vanquished their enemies, they even adopted their gods! Part of the American genius is that we make diversity work, and are constantly striving to implement new, innovative and ingenious ideas in all walks of life, but especially in the technological arena, much as the Romans did.
Militarily, Rome overpowered their enemies with a strategy not unlike that of modern U.S defense policy: concentrating overwhelming combat power quickly and decisively at any flash point of geopolitical conflict within its vast domain. In the Roman era, the network of roads brilliantly planned and constructed throughout the Empire by civil engineers allowed Ceaser to moblize his legions anywhere in Europe within a matter of days. Naval and Air power for the U.S. serve a similar purpose.
But alas, Rome fell, and we will likely share the same fate. Fundamentally, it's just too damn expensive to keep intact the bulwark of "Pax Americana." Among a few of the salient reasons too numerous to itemize in their totality: The aging population, the growing burden of health care, the astronomical price of keeping our technological edge against numerically superior "enemies", the shrinking population of young people in this country to fight battles (or, for that matter, to pay into the Social Security system and the welfare state), and the ridiculous cost of bribing so many other powers around the world, big and small, to do our bidding.
Yes, these are indeed perilous times. In part, because whenever the next American "Ceaser" is elected president, he too lusts for the glory of conquest. Just like the Ceasers of old, our own emperors also march their Legions around the world at the expense of so many other national exigencies that threaten to erode the infrastructure of empire. As our attention is distracted from our domestic needs, we too are overcome by the appeal of bread and circuses.
Anyone wanna guess when Washington gets sacked?