In Life on the Mississippi Mark Twain attributes the southern concept of Chivalry and honor to Sir Walter Scott's Ivanhoe, I've quoted a portion of the text, is there any fact to this idea, or was Twain restricted by his perspective?
Then comes Sir Walter Scott with his enchantments, and by his single might checks this wave of progress, and even turns it back; sets the world in love with dreams and phantoms; with decayed and swinish forms of religion; with decayed and degraded systems of government; with the sillinesses and emptinesses, sham grandeurs, sham gauds, and sham chivalries of a brainless and worthless long-vanished society. He did measureless harm; more real and lasting harm, perhaps, than any other individual that ever wrote. Most of the world has now outlived good part of these harms, though by no means all of them; but in our South they flourish pretty forcefully still. Not so forcefully as half a generation ago, perhaps, but still forcefully.
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Sir Walter had so large a hand in making Southern character, as it existed before the war, that he is in great measure responsible for the war. It seems a little harsh toward a dead man to say that we never should have had any war but for Sir Walter; and yet something of a plausible argument might, perhaps, be made in support of that wild proposition. The Southerner of the American Revolution owned slaves; so did the Southerner of the Civil War: but the former resembles the latter as an Englishman resembles a Frenchman. The change of character can be traced rather more easily to Sir Walter`s influence than to that of any other thing or person.
The heaping of blame upon Scott for the ills of the South is not uncommon (and to be clear, when we talk of the South in this context, for the most part we are talking about the elite planter culture, not the yeomans and plainfolk). Twain is best known for it, as you quote above, but especially in the late 19th to 20th century you could find it elsewhere. A 1917 essay on Scott for instance opined:
So great a movement as the European reaction must have made itself felt in the South in any case, but it may be doubted that the reactionary influence would have been anything like so deep and lasting but for Sir Walter Scott. He was the anti-Rousseau, answering the Social Contract with Ivanhoe. He happened to come, too, at the psychological moment, when the South, bereft of the social ideas of the Revolution, was looking for new idols to replace the broken.
[...]
The new romanticism produced its maximum effect on the imaginative, impressionable South. The planters, who had welcomed the doctrine of equality a couple of decades before, were now convinced aristocrats. In 1795 the social ideal had been the gentleman Jacobin; in 1825 it was Sir Walter's knight. The South, by an effort of the imagination, returned to that medievalism which it has been the special mission of America to combat. Coats-of-arms appeared everywhere-some genuine, some spurious, of course-and the feelings which are expressed by heraldic display became uppermost. The planters turned their backs squarely on modern tendencies. Thus it happened that the Middle Ages, overthrown in the Revolution, conquered in the end. The medieval revival was largely confined to the South.
Of course, the author also goes on to note that "So uninformed are our historians in social phenomena that they have attributed the peculiar trend of Southern life from 1815 to 1860 to the influence of slavery." It only gets worse from there in its "actually slavery had some real positives!" vibes, but in any case, the point is that the author blames the development of the South not only on Scott, but does so quite literally to move blame away from slavery:
The evil of [Scott's] influence lies in the fact that he did so much to put the South out of harmony with the world by which it was surrounded. The South had stood in the full stream of eighteenth century life; it stood wholly aside from the nineteenth century. The chivalric ideal served to check the South's industrial development and social progress. Romantic dilettantism in the course of two generations curbed the energies of the Southern people to a great extent, and for this a price had to be paid.
I don't quote from here to say it's a good argument, only to point out that it is one made in seriousness, and also to highlight just how absurd it sounds in actual full execution, as I don't think you'll find a more extreme position. Twain of course is a man who we might not want to take entirely at face value, but Eckenrode is deadly serious, as were others such as Henry Canby. At its most basic and charitable, you can say that the argument flips cause for effect. It isn't that Scott and works like Ivanhoe caused development of the South in the direction it did post-1820, but rather the works arrived at the right time to be received positively by an audience who felt that the themes of honor and chivalry spoke to them. Scott was popular because it was a society that valued these ideas which Scott seemed to validate; the ideas weren't valued simply because Scott was popular.
And I repeat the if because while of course as any high school student suffering through literature class knows, the Author is Dead, nevertheless there is a decent enough argument that Scott wasn't quite so unambiguous a booster of medieval chivalry and its revivalism. Seelye, for instance, makes a fairly compelling argument that Scott was much more critical that his 19th century audiences took his works to be, but rather much of the Ivanhoe standing as "demonstration of the follies chivalry". Of course, again, the Author is Dead, so it while we can say that Southern audiences may thus have been reading into these works values not entirely intended, it does little to change the fact that they did. But in any case, the take away ought to be that while Ivanhoe and other works of Scott were wildly popular in the antebellum South, it simply demonstrates that those audiences saw similar values expressed in their society echoed in the works.
This isn't to say there is nothing to it, just that it was a different relationship than straight cause and effect. Scott absolutely helped to give further inspiration and direction to the existing impulses developing with South society at the time his works began to make a splash. A revival of mounted tournaments was absolutely a direct result of the Scott craze, for instance, as was the self-styling of many planters as "Southrons", taken from the Waverly romances. Other writers too contributed to this self-conscious styling, such as Sir Edward Bulwer-Lytton, an English novelist, the English poet Lord Byron, or the Irish writer Thomas Moore.
But again, a more critical analysis doesn't give support to Twain's placing of blame for the Civil War, or Eckenrode absolvement of the sins of slavery. It doesn't show us a way of life created as a reaction to exposure to Scott, but rather a society to whom Scott spoke because he reflected an image that they already had of themselves. And while he and other romanticists of the period gave that society color and inspiration for the specific modes of expression, it is just that, a vehicle by which they could self-consciously construct a way to express a nature of their society that was much deeper than Scott's influence.
Sources
Eckenrode, Hamilton James. 1917. “Sir Walter Scott and the South.” The North American Review 206 (743): 595–603.
Osterweis, Rollin G.. Romanticism and Nationalism in the Old South. Yale University Press, 1949.
Seelye, John D. 2001. “Ivan Who?: A Second Look at the Other Book That Is Supposed to Have Started the Civil War.” In Finding Colonial Americas: Essays Honoring J.A. Leo Lemay, edited by Carla Mulford and David S. Shields, 415–33. University of Delaware Press.
Wyatt-Brown, Bertram. The Shaping of Southern Culture: Honor, Grace, and War, 1760s-1890s. The University of North Carolina Press, 2016.