The burning of Jeyne Poore occurred during the Faith Militant uprising.
Late in 45 AC, scores of Poor Fellows were hunted down in the kingswood by the forces of King Maegor I Targaryen. Poxy Jeyne Poore, a woman considered a witch by Maegor's three septons, was eventually betrayed to the king by three of her Poor Fellow followers. Maegor pardoned the three and granted them knighthoods.
Maegor the Cruel ordered that Jeyne be burned alive in a field by the Wendwater. Ser Horys Hill led three hundred Poor Fellows and peasants in an attempt to rescue Jeyne. Maegor was prepared for this eventuality, however, and the king's men slaughtered the would-be rescuers, with Horys among the last to fall. Maegor eventually returned to the Red Keep in 46 AC.