Origin of the expression "to run roughshod over someone"

What is the origin of the expression "to run roughshod over someone"? I have heard it being used by Mitt Romney, but I couldn't find if it has an American origin.

The first instance I can find is in an 1833 speech by Samuel P. Carson in the U. S. House of Representatives, cited in Niles' Weekly Register. It may have been commonly used in conversation before that, but Carson seems to have been the first person to use it in an ink-worthy setting.

I've always been of two minds as to the intended meaning of "rough", which could mean either brutal or rudimentary:

• rough shoes (e.g. baseball spikes) might protect the walker's feet at the expense of what is walked on , or
• rough shoes (e.g. zoris) might indicate that the walker is so confident that what's being walked on is harmless/helpless that no real foot protection is necessary.

I suspect it's the former, but I can see it either way.

Either way, it expresses indifference - but what kind?

The phrase is more commonly to "ride roughshod over [someone or something]" rather than to run, which shows its equine roots.

Merriam-Webster gives a first known use of the adjective as circa 1688 and defines it as:

1 : shod with calked shoes
2 : marked by tyrannical force <roughshod rule>

They give a first known use for the adverb as 1813 and define it:

in a roughly forceful manner < rode roughshod over the opposition >

The Word Detective says:

The original literal meaning of “to ride roughshod” was far more brutal. In the 17th century, a horse that was “roughshod” was shod with horseshoes with the nailheads, or sometimes metal points, projecting from the bottom of the shoe. This gave the horse better traction on slippery ground or ice. But when cavalry horses were “roughshod,” they became brutal weapons in a charge against foot soldiers. As bad as being trampled by a horse must be, being struck by “roughshod” hooves is apparently far worse.

As an aside, roughshod horses could accidentally injure themselves by striking a hindfoot against a forefoot, and the 1726 Dictionarium Rusticum, Urbanicum & Botanicum gives an unappealing cure:

I found an earlier use of our phrase, amongst a list of "Toasts, Sentiments, Hob-nobs, &c."in a book called The Bird, published in London in 1781:

Health to all honest men a trip up to all scoundrels and may the devil ride rough-shod over the rascally part of the creation.

According to 1793's The Festival of Wit, this very toast was reportedly used after a dinner given by a Major Rogers at his new house at Southhampton Buildings, Holborn, London.

In fact, the earliest citation of the phrase in OED is this same sentence, attributed to Aristophanes in 1778:

"The d—l ride rough-shod over the rascally part of the creation."

This UK use is probably more literal, and a possibly more idiomatic use occurs later in the US.

It appears in the Report of the trial and acquittal of Edward Shippen, Esquire, Chief Justice and Jasper Yeates and Thomas Smith, Esquires, Assistant Justices, of the Supreme Court of Pennsylvania on an Impeachment, Before the Senate of the Commonwealth from 1805:

I regret that my worthy friend has rode rough shod over the character of this poor man when it is the act of the House of Representatives and not his.

But back in the UK, Sir Walter Scott used it in a poem called Lord Ewrie (published in 1810's Ministrelsy of the Scottish Border, although first published 1802), possibly literally, but the context suggests the idiomatic use as well:

With our queen's brother he hath been
And rod rough shod through Scotland of late
They have burned the Mers and Tiviotdale
And knocked full loud at Edinburgh gate

Finally, two from 1819:

• Niles' Weekly Register, Baltimore, US: "Gracious heaven!-are such things to be, that tifty men may "ride rough shod, over a ruined people — a great and gallant nation, the pride of the world, and hope of posterity.?"

• Blackwood's Edinburgh Magazine, Edinburgh, UK: "Shall rough-shod ride o-er church and state, Then hey! for DonGiovanni." ... " We shall ride roughshod over Carlton House." — Speech of all the talents through the mouth-piece of Lord ------, on hearing of the assassination of Mr Percival.

A quick Google implies that it is about horses being shod with projecting nail, to prevent slippage.

Of course, riding a horse like this over ground - or a person - would result in serious damage. It suggests that a concern for the horse overrides concern for the ground or whatever is being ridden over. I would guess that it may have a reference also to riding over a battlefield, which may be slippery with blood, and riding your horse roughshod would enable it to grip and move on. And kill anyone not dead underneath you.