He had been taken prisoner following the Crusader - Syrian defeat at the Battle of La Forbie where he had led the Crusader Army against the Egyptian forces .
Mary became a widow in October 1244 after Walter was murdered in Cairo .
Walter had been taken prisoner following the Crusader - Syrian defeat at the Battle of La Forbie where Walter had led the Crusader Army against the Egyptian forces .
Mary became a widow in October 1244 after Walter was murdered in Cairo .