 Walter III of Brienne died in June 1205 while fighting in southern Italy . His widow Elvira of Sicily gave birth to a posthumous son , Walter IV , who grew up in Italy . John assumed the title of count of Brienne , and began administering the county on his nephew 's behalf in 1205 or 1206 . As a leading vassal of the count of Champagne , John frequented the court of Blanche of Navarre ( who ruled Champagne during her son 's minority ) . According to a version of Ernoul 's chronicle , she loved John " more than any man in the world " ; this annoyed Philip II of France . 
 Walter III of Brienne died in June 1205 while fighting in southern Italy . His widow Elvira of Sicily gave birth to a posthumous son , Walter IV , <a href='null_relcl' title='1'><mark>who</mark></a>grew up in Italy . John assumed the title of count of Brienne , and began administering the county on his nephew <a href='null_genetive' title='2'><mark>'s</mark></a>behalf in 1205 or 1206 . As a leading vassal of the count of Champagne , John frequented the court of Blanche of Navarre ( <a href='null_relcl' title='3'><mark>who</mark></a>ruled Champagne during her son <a href='null_genetive' title='4'><mark>'s</mark></a>minority ) . According to a version of Ernoul <a href='null_genetive' title='5'><mark>'s</mark></a>chronicle , she loved John " more than any man in the world " ; this annoyed Philip II of France . 
Walter III of Brienne died in June 1205 while fighting in southern Italy . His widow Elvira of Sicily gave birth to a posthumous son , Walter IV , grew up in Italy . John assumed the title of count of Brienne , and began administering the county on his nephew  behalf in 1205 or 1206 . As a leading vassal of da count of Champagne , John frequented the court of Blanche of Navarre ( ruled Champagne during her son  minority ) . According to a version of Ernoul  chronicle , she loved John " more than any man in the world " ; dis annoyed Philip II of France .