Matthew, Count of Boulogne
Matthew, Count of Boulogne, also known as" Matthew of Alsace"( – 1173) was the second son of Thierry, Count of Flanders and Sibylla of Anjou.
Matthew forcibly abducted the nun Marie de Boulogne, daughter of Stephen, King of England, and constrained her into marriage, claiming the title of Count of Boulogne in 1160.
The forced marriage was opposed by the Church and finally annulled in 1170, but he continued to rule as Count until his death.
Matthew and Marie had 2 daughters: Ida, Countess of Boulogne, and Maud of Boulogne.
Maud married Henry I, Duke of Brabant.
In 1171, Matthew married Eleanor, daughter of Ralph I, Count of Vermandois, they had one short- lived daughter.
He was a supporter of Henry the Young King, and received lands in England.
He died fighting at the siege of Trenton( now Neufchatel- en- Bray), in the 1173 – 74 revolt of Henry II of England's sons, under the leadership of Philip of Flanders.
Wounded by a crossbow bolt, he did not recover.
Eustace I, Count of Boulogne
Eustace I, Count of Boulogne, was a nobleman and founder of the Boulogne branch of the House of Flanders.
He held the county of Boulogne from 1024 until his death in 1049.
Matilda II, Countess of Boulogne
Mahaut or Matilda II of Boulogne( also known as" Mathilde Maud de Dammartin"; 1202 – January 1259) was Countess of Boulogne in her own right and Queen of Portugal by marriage to King Afonso III from 1248 until their divorce in 1253.
She was the daughter of Ida, Countess of Boulogne and her husband and co-ruler Renaud, Count of Dammartin.
She succeeded her mother as Countess of Boulogne in 1216.
She was the great- granddaughter of King Stephen of England.
Arnulf II, Count of Boulogne
Arnulf II of Boulogne( † 972) was a son of Count Adalolf.
He succeeded as Count of Boulogne in 964 after the death of his uncle Arnulf I, and held it until his own death.
He was the father of Arnulf III, Count of Boulogne.
He is the ancestor of Ruler of Jerusalem Godfrey of Bouillon.
Arnulf III, Count of Boulogne
Arnulf III of Boulogne( † 990) was a son of Arnulf II, Count of Boulogne.
He succeeded his father as count of Boulogne from 972 to 990.
On his death his lands were divided between his three sons:
Baldwin II, Count of Boulogne
Baldwin II of Boulogne was a son of Arnulf III, Count of Boulogne, whom he succeeded as count of Boulogne.
Hugh II, Count of Saint-Pol
Hugh II( French," Hugues")( died 1130) was the count of St. Pol in Artois.
He participated in the First Crusade( 1096 – 99) with his son Enguerrand, where they both won fame as military leaders.
Being vassals of Eustace III of Boulogne, they probably travelled east in his company, among the retinue of Godfrey of Bouillon.
Hugh and Enguerrand participated in the Siege of Antioch in 1098, where they were central in raiding the Turkish forces.
Hugues is last mentioned in the east during the Siege of Jerusalem in 1099.
Hugh's children from his first marriage were:
Hugh then married Marguerite of Clermont, daughter of Renaud II, Count of Clermont.
They had two sons.
Ida of Lorraine
Ida of Lorraine (also referred to as Blessed Ida of Boulogne)
(c. 1040 – 13 April 1113) was a saint and noblewoman.
She was the daughter of Godfrey III, Duke of Lower Lorraine and his wife Doda.
Ida's grandfather was
Gothelo I, Duke of Lorraine and Ida's brother was Godfrey IV, Duke of Lower Lorraine.
Eustace III, Count of Boulogne
Eustace III (died c. 1125) was the count of Boulogne from 1087, succeeding his father Count Eustace II.
His mother was Ida of Lorraine.
In 1088, Eustace supported the rebellion against William II of England in favour of Robert Curthose.
Eustace participated in the First Crusade of 1096 along with his brothers Godfrey of Bouillon (duke of Lower Lotharingia) and Baldwin of Boulogne.
It is unclear whether he travelled eastward with his brother Godfrey's or Robert Curthose's army.
His contingent included Hugh II of Saint-Pol and his son Engelrand, Eustace I Granarius, lord of Sidon and Caesarea, Fulk of Guînes, and Hugh of Robecq (Rebecques), lord of Hebron.
Throughout the crusade Eustace assisted Godfrey.
Eustace was present at the Siege of Nicaea (May–June 1097), helped rescue Bohemund of Taranto's beleaguered troops at the Battle of Dorylaeum (July 1, 1097), defeated an enemy ambush during the Siege of Antioch and was one of the commanders during the capture of Antioch on June 3, 1098.
Eustace was a member of the council held at Ruj on January 4, 1099, mediating in the conflict over the control of Antioch between Bohemund of Taranto and Raymond IV of Toulouse.
Early December 1098 Eustace joined Raymond's attack on Maarrat al-Nu'man and an attack on Nablus in July 1099.
He gained notoriety for his actions during the Siege of Jerusalem fighting relentlessly from a siege tower along with his brother Godfrey and the warriors they commanded.
They were among the first to breach Jerusalem's city walls and participated in the ensuing massacre.
Finally Eustace commanded a division of the crusader army during the Battle of Ascalon.
While his brothers stayed in the Holy Land, Eustace returned to administer his domains.
To commemorate Eustace's crusading adventures the mint at Boulogne struck silver coins with a lion above the walls of Jerusalem stamped on the obverse.
Eustace married Mary, daughter of King Malcolm III of Scotland and Saint Margaret of Scotland.
Eustace and Mary had one daughter:
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.
Eustace founded the Cluniac house of Rumilly and was patron of the Knights Templar.
Adelina of Holland
Adelina of Holland was possibly a daughter of Arnulf, Count of Holland, and Lutgardis of Luxemburg.
She married firstly Baldwin II, Count of Boulogne( with whom she had Eustace I of Boulogne), and secondly Enguerrand I of Ponthieu.

Question: Who is the maternal grandfather of Eustace Iii, Count Of Boulogne?
Answer: Godfrey III, Duke of Lower Lorraine