If a gentleman issued or accepted a challenge in proper form and, fought like a gentleman, with a gentleman, then to be vanquished; was no defeat. Certainly it was nobler than suffering the insult or refusing the fight. And to be killed in a duel by your equal was, if not exactly a pleasure, at least honorable. Your grandchildren could tell of it proudly.
Courage, not manners, was the hallmark of a gentleman. As the duel epidemic spread, courage came to mean a thin skin and an unruly temper, the thinner and more unruly, the more gentlemanly. A gentleman was proud of his temper and indulged and cherished it. There may have been, off in remote country estates, phlegmatic gentlemen landowners, waistcoats bulging with good claret and venison, who chuckled at insults, waved them away, and opened another bottle, but in the cities, the armies, and the universities, prickliness was a point of pride, as proud youths in tough neighborhoods are quick to avenge being “dissed.” An easygoing temperament meant your blood was slow, and cold, and lowly.
In The Three Musketeers, the noble Aramis studies in the seminary for ten years to fulfill his dream of becoming an abbé, but a jealous officer insults him, and he quits the seminary and goes off to take fencing lessons daily for a year. Then he finds the officer, calls him out, and strikes him dead. “I am a gentleman born—my blood is warm,” he explains.
In The Tempest, Prospero threatens Ferdinand, son and heir to the king of Naples, and Ferdinand promptly draws his sword. Miranda cries, “0 dear father, make not too rash a trial of him, for he’s gentle, and not fearful.” By gentle, she doesn’t mean he’s kind to dogs and small children. She means he’s well-bred, and therefore bad tempered, armed and dangerous. Not to be trifled with.
As its first definition of “gentle,” the Oxford English Dictionary, both feet stubbornly planted in the past, gives “well-born, belonging to a family of position; originally used synonymously with noble, but afterwards distinguished from it, either as a wider term, or as designating a lower degree of rank. Also, in heraldic use: Having the rank or status of ‘gentleman,’ the distinguishing mark of which is the right to bear arms.”
Gentlemen bore arms. In the Scottish Highlands, where nobody would think of leaving the house without a sword, or perhaps even sitting down to dinner without one, true gentlemen distinguished themselves from their lowlier neighbors by a feather in the bonnet as well—as in “a feather in his cap”—but elsewhere only gentlemen were entitled to the sword. Swords were the badge of a man who needed no help “beyond that of his heart, his sword, and his valor.” The French called it “la noblesse de l’epee.”
— Gentlemen’s Blood, p. 28-29
Emphasis mine.