I decided to do a separate post for the Republic vs. Empire question.
We used to have a clear division between "Fleet" and "Ground operations in our military. "Fleet" meant Navy and Marines; they were the ones who patrolled the world to keep the sea lanes safe for American commerce, to assist allies in small operations, to extract U.S. and friendly citizens trapped in nasty places, to assist in disasters on the seas and within reach of their forces. "Ground" was the Army, and the function of Ground was to go after the enemy, crush his forces, and announce a victory because the enemy had nothing left. Ground went into business when the President had identified an enemy and Congress had formally declared war, and when Ground did, Fleet shifted to take on a support role, aiding by coastal bombardment, but mostly retained its standard role, albeit one adjusted to live fire protection against hostile vessels, to make sure the Ground could keep getting its supplies and do its job.
Air power was ambiguous. It functioned on the one hand as a sort of 'super-artillery', able to go out and clobber enemy resources not just on the battlefield, but beyond it, and operating in this fashion was a Ground force, but on the other hand it carried out the support functions of the Fleet.
This form of operations depended on something important: an educated citizenry with loyalty to country and a grasp of the principles and virtues that make a Republic strong and keep it free. But we've lost those. Through a focus on direct democracy, and every special interest group from labor to gays to giant corporations fighting not for all but for a piece of the pie for themselves, the virtues of a Republic have been lost. Hardly anyone these days asks what they can do for their country rather than for themselves. That's dangerous, because the military forces of a Republic depend on the virtues of a Republic for their cohesion: in World War I there was no need to spend time instilling military virtues, because those virtues are the virtues of a Republic. Loyalty to one's company grew out of a shared loyalty to the Republic, and indeed loyalty to the Republic ranked higher than that to the unit.
There's no way the military can instill the virtues of a Republic into its recruits. That's the job of the schools, and they've failed miserably. Yet the military still needs unit cohesion, which means unit loyalty. Without the virtues of a Republic, unit cohesion can only rest on the only common loyalty available: to the unit itself. That's a form of loyalty known since the Roman legions happily toppled Roman cities and tackled other Roman armies: they had no loyalty to Rome; there was no concept of Rome at all as being theirs, only as a paymaster and taskmaster and hopefully the source of a small farm when they retired. Loyalty to unit meant they had no problem fighting other units, or even marching on the capital. Theirs was the military virtue set of Empire, which easily tipped loyalty to unit into loyalty to commander. That, in fact, is where we get the word "imperator", from which we get "emperor": it meant someone hailed by the troops as worthy to command.
So what we get in today's military are the virtues of an empire, not of a Republic. This gets reinforced as presidents use the military, especially the Ground, as more or less a private army to achieve their own goals: the command structure of Empire, not of Republic. They have turned Ground into what Fleet has always been, a way to throw forces into the equation without a declaration of war.
And when we get veterans of such a system, they emerge not with loyalty to a Republic, but to the military itself. They are trained to respond to the chain of command; only rarely do they even have the capacity to question the chain of command on the basis of the virtues of a Republic. Ironically, the greatest encouragers of this trend with the military have been those elected officials who call themselves "Republican".
Apart from the military, the same process goes on: we have a flood of immigrants who know nothing of the virtues of a Republic. Their heritage culturally is of Empire. They understand bowing to authority and doing what it says; they do not grasp that the greatest thing a citizen can do in a Republic is to not merely question, but be suspicious of authority. And for at least a generation, our public schools have failed to instill the virtues of a Republic, so that even our home-grown citizens are tuned to Empire.
Taken all together, this means that we as a nation are primed to think in terms of bowing to government's wishes, not to defying it or questioning it. That is a disease that makes us, if not an Empire in actuality, an incipient one. It is, furthermore, a disease that has been fed by the unrestrained growth of a federal government which contrary to the supreme law of the land assigns to itself more and more authority over more and more aspects of life, until citizens obey without thinking, trained in the habit of obedience to authority.