On May 21, 1216, French crown prince Louis entered England having been invited by barons at war with King John. A short excerpt:
"Numerous Barons revoked their fealty to John and invited Prince Louis of France, a maternal grandson of Henry II, to invade and take the English throne. Initially John went on the offensive devastating the lands of the rebel Barons and mounting a legendary siege against Rochester Castle. However French Knights arrived in London in November 1215 and in May the following year, Louis landed in Kent. John retreated west and Louis entered London without opposition where he was proclaimed King. By Summer 1216 he had overrun much of southern England although Dover and Windsor castles bitterly resisted his forces."