Eustace III, was a
count of Boulogne, successor to his father Count
Eustace II of Boulogne. His mother was
Ida of Lorraine.
His father Eustace II appeared at the
Battle of Hastings in 1066 as an ally of
William the Conqueror, and is listed as a possible killer of
Harold II; he is also believed to have given William his own horse after the duke's was killed under him by
Gyrth, brother of Harold.
Eustace III succeeded as
Count of Boulogne in 1087.
[1]He went on the
First Crusade in 1096 with his brothers
Godfrey of Bouillon (
duke of Lower Lotharingia) and
Baldwin of Boulogne. He soon returned to Europe to administer his domains. He married
Mary of Scotland, daughter of King
Malcolm III of Scotland, and
Saint Margaret of Scotland. Eustace and Mary had one daughter,
Matilda of Boulogne.
When his youngest brother king
Baldwin I of Jerusalem died in 1118, the elderly Eustace was offered the throne. Eustace was at first uninterested, but was convinced to accept it; he travelled all the way to
Apulia before learning that a distant relative,
Baldwin of Bourcq, had been crowned in the meantime. Eustace returned to Boulogne and died about 1125.
On his death the county of Boulogne was inherited by his daughter, Matilda, and her husband
Stephen de Blois, count of
Mortain, afterwards king of England, and at the death of Matilda in 1152 it was inherited by their son,
Eustace IV of Boulogne, later their second son William and ultimately by their daughter
Marie of Boulogne, since both sons died without children.