National Children's Book Week begins today. The celebration of children—and of literature for children—calls to mind the folktale "The Pied Piper of Hamelin" and the real-life story thought to be behind it: the Children's Crusade.

For almost two hundred years, beginning just before the 12th century, wave after wave of Christian pilgrims and armies attempted to wrest control of the Holy Land from its Muslim inhabitants. Although the doomed campaigns resulted in the deaths of thousands of Christians and Muslims alike, the Children's Crusade stands out as an especially horrific episode.

That ill-fated Crusade began in the summer of 1212 after a French shepherd boy reported a religious vision of Jesus. More than 30,000 children flocked to his banner, and a second group of at least 20,000 children took up the standard of a ten-year old German boy. The French children made it as far as Marseilles, where they fell into the hands of slave traders. The luck of the German children was slightly better; after they crossed the Alps, they divided up. Some actually made it back home after a sympathetic pope released them from their vows. The tragedy of the German children is said to have inspired the legend about the rat-catcher of Hamelin, while the phrase "children's crusade" has come to refer to any enterprise led by the inexperienced and idealistic young.

There is a Dutch children's book about the Children's crucade. I don't know if it has been translated in English. It is by Thea Beckman and is called 'Kruistocht in spijkerbroek'. By age 15 I had read it about 7 times.