sentence: origin of the earls of lancaster seal of edmund crouchback after the supporters of henry iii of england suppressed opposition from the english nobility in the second barons ' war , henry granted to his second son edmund crouchback the titles and possessions forfeited by attainder of the barons ' leader , simon de montfort , 6th earl of leicester , including the earldom of leicester , on 26 october 1265 .