 By 1419 Henry V occupied much of Normandy and demanded an oath of allegiance from the residents . The new Duke of Burgundy , Philip the Good , allied with the English , putting enormous pressure on France and Isabeau , who remained loyal to the King . In 1420 Henry sent an emissary to confer with the Queen , after which according to Adams , Isabeau " ceded to what must have been a persuasively posed argument by Henry V 's messenger " . France had effectively been left without an heir to the throne , even before the Treaty of Troyes . Charles VI had disinherited the Dauphin , whom he considered responsible for " breaking the peace for his involvement in the assassination of the duke of Burgundy " ; he wrote in 1420 of the Dauphin that he had " rendered himself unworthy to succeed to the throne or any other title " . Charles of Orléans , next in line as heir under Salic law , had been taken prisoner at the Battle of Agincourt and was kept in captivity in London . 
