I'm listening to H.W. Brands' biography of Andrew Jackson and Brands puts forward a story I hadn't heard of before. At the beginning of the chapter following Jackson's victory at the battle of New Orleans, Brands paints a picture of an America not just ready to fall, but falling. With points such as the ruins of DC and the "seditious" Federalist convention at Hartford, Brands suggests that the United States were, at best, about to become simply disunited. Of course, he is doing all this in order to name Jackson the savior of America, but, bias aside, I wonder how far off the mark he really is.
Is Brands' portrayal of an all but toppled America accurate?
The image of a United States falling to absolute pieces is not necessarily inaccurate, but the picture would look more or less severe depending on where you stood. I'll break my answer into a few parts, talking about some of the real and perceived threats to the union of the United States in late 1814.
Federalist "Sedition"
The war was always deeply divisive in the United States (more here, and there was talk from Federalist opponents - to the war specifically and to the Madison administration (and the Jeffersonian political trend) in general - of northern secession, but Hugh Howard has argued that the Federalists used talk of disunion as a saber-rattling threat rather than a real plan of action. And the Hartford Convention was hardly the first time that political opponents to the standing administration had talked of secession; Timothy Pickering had argued since as early as 1804 that secession was the only way to avoid "Mr. Jefferson's plan of destruction." The belief, among Federalists, that the populist streak in Democratic-Republican politics would be ruinous to the country was old hat even by then. I've written more before on Federalist political beliefs in terms of the 2nd amendment and the general political beliefs of the Early Republic, and I want to stress here that the Federalists were not, as has been popular in recent historiography, just "sore losers" or animated by particularly anti-patriotic feelings; they simply believed in a different method of structuring government for the common good.
However, because there was a belief (predominantly, no surprise, from the party-in-power) that the war necessitated a need to pull in the same direction, so to speak, and so the Madison administration, and Jeffersonian devotees, saw Federalist opposition to the war as a brand of political sabotage. It was described as "party frenzy," and "party politics" were assumed to be behind the somewhat notorious militia indiscipline during several border-crossing attempts in the early phases of the war. Personally, I think that belief in an unfair characterization, but it was believed by many at the time.
Fiscal Insolvency
But political resistance was not the only threat to the country. By 1814, banks were no longer willing to extend credit to the United States to pay for the war. Supplies to troops in every theater were stretched thin, and lack of pay, supply shortages, indifferent logistical support were omnipresent issues to the small United States army.
But if the country were allowed to fail in paying the debts accrued during the war, it would have made fuel for the Federalists, proof that the war had been a foolish waste of capital, of American lives, and a permanent stain on the American reputation. We can't really know what might have happened if the war dragged on for even another few months, but it doesn't seem an extreme conjecture to think that the Madison administration would likely have been viewed as a failure, and it may have brought renewed strength to the Federalist opposition.
Conquest
The British had struggled to find the men and the materiel through the early stages of the war, and relied heavily on American Indian allies and Canadian militia and irregulars to bear a large burden of fighting, but by 1814, with the war in Europe coming to a close, and the full active might of the Royal Navy and the prospect of shipping tens of thousands of experienced, hardened veterans of the Napoleonic Wars to North America, the prospect of not only losing the war but losing very badly seemed extremely real. We know from hindsight that logistical problems were much, much larger than simple manpower could overcome, but we can't underestimate the effect this had on the country's morale.
I haven't read Brands' work, but I can say with some authority that Jackson wasn't some singular hero in the American mind; he was one of an entire generation of military and political leaders that based much of their reputation on their performance in the war.
I hope that helps? It's difficult to plumb the mind-state of people two hundred years gone, but there was certainly a sense of fear and uncertainty for what looked more and more, until the astonishing victories at the end of 1814, that the country was doomed to lose a war, splinter into "party frenzy" and suffer disunion.
Jon Latimer's 1812: War with America and Donald Hickey's The War of 1812: A Forgotten Conflict are the two best overall histories of the war. You might enjoy reading Nicole Eustace's 1812: War and the Passions of Patriotism for a more specific look at the metaphorical/philosophical elements of the war.