German town records in Hamelin long preserved June 26, 1284 as the date connected to the Pied Piper legend of rats and vanished children, though some later chronicle traditions and civic records reference related anniversary observances in surrounding centuries, including July dates, reflecting the tale's murky blend of folklore and documented town disaster.
The oldest trace of the story in Hamelin was not a book but a window. Around 1300, the town's Market Church installed stained glass showing a colorfully dressed piper and a procession of children in white. The glass was destroyed in 1660, but descriptions and a later copy survive, and they suggest that within a generation or two of the event Hamelin was commemorating a real loss. A manuscript from about 1440 to 1450, now known as the Lüneburg manuscript, gives the earliest written account: in 1284, on the feast of Saints John and Paul, 26 June, 130 children born in Hamelin were led away by a piper dressed in many colors and were lost near a place called the Koppen, outside the town.
The rats came later. The early sources describe only the piper and the missing children; the plague of vermin, the unpaid fee and the piper's revenge were attached to the tale in the sixteenth century, turning a communal grief into a moral fable about broken promises. Historians have proposed many explanations for the original disappearance, including plague, a pilgrimage or children's crusade, an outbreak of dancing mania, and, most persistently, the recruitment of young townspeople to settle new lands in the east during the medieval German migration into Central and Eastern Europe. None of these theories has been proved.
As the story traveled, its date drifted. English retellings placed it on July 22, 1376, and Robert Browning fixed that version in his 1842 poem "The Pied Piper of Hamelin," written for a sick child, which made the legend a staple of English-language nursery reading. Hamelin itself holds to the older tradition, and it keeps one small, striking custom: on the Bungelosenstrasse, the "street without drums" along which the children are said to have been led, music and dancing are still forbidden, even during wedding processions.