Who were the most powerful men in england at the time of the outbreak of the 100 years war, 1337?

Question

I already have listed:

Richard Grosmont, 1st Duke of Lancaster

Edward III, King of England

Answer 1

Richard Neville, 16th Earl of Warwick, also called "the Kingmaker" who was killed at the Battle of Barnet on April 14th, 1471 in a fight against the forces of King Edward IV. More information is readily available online.