This book is about chivalry, but not as it was known in the Middle Ages, as it was revived in the Victorian era -- as an ethos rather than a military code -- in Great Britain.
It touches on Sir Walter Scott who revived interest in it despite his distaste -- he regarded the code of manners of his own day as immensely preferable -- and Kenelm Digby, whose Broad Stone of Honour was immensely popular and treated it as an ethos applicable to the modern day and indeed preferable to it, and whose disdain for making money and trade, and intellectualism, were deeply if not always fortunately influential. Describes the unfortunate Eglinton Tournament and how Victoria came to be interested in chivalry and medievalism (chiefly Albert, actually).
And it touches on how it influenced all sorts of areas. Architecture, some -- public schools, Boy Scouts, Muscular Christianity, politics of all stripes, Imperialism (where it was less common as a motif, Imperial Rome being favored, but still appeared), Arthurian literature, and courtly love. (The mainstream Victorian chivalry emphasized chastity far more than the medieval version, but there were strains of courtly love, too.)
And World War I and how hard it was on the chivalric ethos.
An interesting study in the evolution of an attitude and how it got used in all sorts of setting and what parts got emphasized -- or used at all -- where.