Year 1404 (MCDIV) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. Events of 1404 June 14 – Rebel leader Owain Glyndŵr, having declared himself Prince of Wales, allies with the French against the English. He later begins holding parliamentary assemblies. October 17 – Pope Innocent VII succeeds Pope Boniface IX as the 204th pope. November 19 – St. Elizabeth's flood devastates parts of Flanders, Zeeland and Holland. Stefa… (More on 1404)