which military conflict took place in county of flanders and had commander as william longespée ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_place dbr_County_of_Flanders sep_dot var_uri dbo_commander dbr_William_Longespée,_3rd_Earl_of_Salisbury sep_dot var_uri a dbo_MilitaryConflict brack_close