 Montfort 's coalition began to quickly fragment , Henry regained his freedom of movement and renewed chaos spread across England . Henry appealed to his brother @-@ in @-@ law Louis of France for arbitration in the dispute ; Montfort was initially hostile to this idea , but , as war became more likely again , he decided to agree to French arbitration as well . Initially Montfort 's legal arguments held sway , but in January 1264 , Louis announced the <unk> of Amiens , condemning the rebels , upholding the King 's rights and <unk> the Provisions of Oxford . The Second Barons ' War finally broke out in April , when Henry led an army into Montfort 's territories . Becoming desperate , Montfort marched in pursuit of Henry and the two armies met at the Battle of Lewes on 14 May . Despite their numerical superiority , Henry 's forces were overwhelmed . <unk> , Henry was forced to pardon the rebel barons and reinstate the Provisions of Oxford , leaving him , as historian Adrian <unk> describes , " little more than a <unk> " . 
