Task: Question Generation
Input (English): Prince Louis intended to land in the south of England in May 1216, and John assembled a naval force to intercept him. Unfortunately for John, his fleet was dispersed by bad storms and Louis landed unopposed in Kent. John hesitated and decided not to attack Louis immediately, either due to the risks of open battle or over concerns about the loyalty of his own men. Louis and the rebel barons advanced west and John retreated, spending the summer reorganising his defences across the rest of the kingdom. John saw several of his military household desert to the rebels, including his half-brother, William Longespée. By the end of the summer the rebels had regained the south-east of England and parts of the north.
Output (English): When did the rebels regain the south-east of England?