Pied Piper of Hamelin
The Pied Piper was promised a reward if he would drive the rats and mice out of Hameln (Westphalia). This he did, for he gathered them together by his pipe, and then drowned them in the Weser. As the people refused to pay him, he next led the children to Koppelberg Hill, where 130 of them perished (July 22nd, 1376). (See Hatto.)
To blow the pipe his lips he wrinkled, And green and blue his sharp eyes twinkled ... And ere three notes his pipe had uttered ... Out of the houses rats came tumbling- Great rats, small rats, lean rats, brawny rats, Brown rats, black rats, grey rats, tawny rats, And step by step they followed him dancing, Till they came to the river Weser.
Hameln, on the river Hamel, is where the Rattenfänger played this prank. It is said that the children did not perish in the mountain, but were led over it to Transylvania, where they formed a German colony.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894