Matthew of Alsace Count of Boulogne (1137–1173) Parents Sibylla of Anjou Thierry of Lorraine, Count of Flanders Children Matilda of Flanders Ida, Countess of Boulogne Siblings Philip I, Count of Flanders Margaret I, Countess of Flanders Gertrude of Flanders, Countess of Savoy Peter of Flanders Laurette of Flanders Matilda de Flandre Baldwin de Flandre Partners Eleanor, Countess of Vermandois Marie I, Countess of Boulogne