What were the main reasons why William and Harold lost?

Answer 1

William was more properly ready and this was harolds second fight of the day. some of harolds best fighters had died in the battle of the stamford bridge

Reasons why William won:

-luck,the arrow which hit Harold,harvest time so some of the fyrd went home,storm which forced Harold into the hands of William,the fake retreats,arrival of hadraada,William survived the blow,wind blowing the opposite way accross the cannel,

-harolds weaknesses,untrained fyrd,lack of control,no calvery/archers,rused into battle,failed to defend coast,tactically unflexible,

-Williams strengths,brave,professional force,well equiped,tactically aware,

-Tostig and hadraada,the battle at stamford bridge led Harold to becoming too confident,harolds army was tired,Harold had to leave the south ungarded,Harold lost a 1/3 of his housecarls.