Louis immediately attempted to persuade the garrison to accept him as king in preference to the young Henry but the garrison, having no quarrel with Henry, declined his offer.
After almost three months spent at Dover, Louis set off for London only to return on the 12th of May 1217 to attempt to capture Dover castle once again. This time a trebuchet was employed but, just as the mangonels and perriers had failed, so did the trebuchet. Matthew Paris referred to this awesome piece of medieval artillery, calling it the "Malvoisin" (the bad neighbour).
Luck turned from bad to worse for the French prince when half of his army were killed at the battle of Lincoln on the 20th of May. On hearing of this defeat Louis dismantled his trebuchet and once again returned to London.
Worse news was to follow. The decisive sea battle at Sandwich on the 24th of May, which prevented reinforcments from France, was to