"[There once was a] dragon killer of the Dark Ages by the name of Gerolde. He acquired during his lifetime a large and faithful following of people eager to hear of his dragon-slaying exploits. For many years he roamed the countryside seeking dragons and other evil creatures, speaking out against them, and burning any books that mentioned dragons or their kin. He was eventually made a knight and was dubbed Gerolde-the-Good, because of his obvious piety. His minions formed what was probably the first fan club in history and referred to themselves as the pious multitude, whose major goal was to seek out and destroy sin in all of its many forms.
The first dragon that Gerolde slew was a relatively small one (evidently only about twenty feet long) that he managed to surprise one day while dressed in his shiniest suit of armor and riding his charger. Without a thought for his own safety, he attacked the beast. The reflections of the sun off shiny armor dazzled the dragon, and before it could retaliate, it found itself fatally impaled on Gerolde's long lance. Gerolde was immediately hailed as the greatest of all dragon killers, and he was swamped with requests to speak before civic groups and to clear dragons out of various strongholds.
He traveled about the land with his entourage and was offered rich presents and rewards for his good deeds. Among these were numerously brightly colored silk garlands and ribbons, which well-wishers begged he would attach to his lance or his helmet for good fortune. Finally, Gerolde had the clever idea of making an entire multicolored jacket of these ribbons, which he could slip over his armored suit. He was immediately transformed into a flaglike vision of blue, white, red, and green.
Shortly thereafter, clad in his colorful garment, he encountered a large dragon and attacked it with full confidence in his invulnerability. This time the reflective armor was effectively hidden by the jacket, and the sun was hidden by clouds. The dragon, upon being attacked, released a vast amount of fire, incinerating Gerolde on the spot. His followers were badly shaken by this turn of events but nevertheless recovered his charred remains and returned to town. He was buried in a nearby cathedral, with all possible honors. On his grave a simple epitaph was engraved in Latin, which in translation read: 'Never wrap yourself in a flag when you go forth to slay dragons.'"
- from Dragons and Unicorns: A Natural History by Paul and Karin Johnsgard