When I read Notker the Stammerer’s biography of Charlemagne, composed about 70 years after the emperor’s death, I get the feeling that he didn’t let facts get in the way of his story.
I suspect he fabricated the tale about Charlemagne and his noblemen going on hunt in the clothes they were all wearing right at the moment. Charlemagne had a sheepskin cloak, while the others were adorned in silks and other fragile finery to trek through thorns and rain.
The tale is moralistic about vanity—and subversive. Lay noblemen were expected to flaunt their wealth and chose clothes with pricey materials. The more reliable Einhard has Charlemagne favoring a tunic fringed with silk and a vest of expensive otter and marten furs. The king’s swords had silver and gold hilts. For special occasions, he had embroidered garments, jeweled shoes, a golden buckle for his cloak, and a diadem.
To have a king to wear a sheepskin cloak, something a commoner would have, is a tad rebellious. But Notker does have a point: there are times when the humble item is of great value. See my post on English Historical Fiction Authors about the durability and practicality of this piece of medieval fashion.