Siege of Antioch in the context of "Eustace III, Count of Boulogne"

The Holy Lance, also known as the Spear of Longinus (named after Saint Longinus), the Spear of Destiny, or the Holy Spear, is alleged to be the lance that pierced the side of Jesus as he hung on the cross during his crucifixion. As with other instruments of the Passion, the lance is only briefly mentioned in the Christian Bible, but later became the subject of extrabiblical traditions in the medieval church. Relics purported to be the lance began to appear as early as the 6th century, originally in Jerusalem. By the Late Middle Ages, relics identified as the spearhead of the Holy Lance (or fragments thereof) had been described throughout Europe. Several of these artifacts are still preserved to this day.

Holy Lance relics have typically been used for religious ceremonies, but at times some of them have been considered to be guarantees of victory in battle. For example, Henry the Fowler's lance was credited for winning the Battle of Riade, and the Crusaders believed their discovery of a Holy Lance brought them a favorable end to the Siege of Antioch.

The County of Edessa (Latin: Comitatus Edessanus) was a 12th-century Crusader state in Upper Mesopotamia. Its seat was the city of Edessa (modern Şanlıurfa, Turkey).

In the late Byzantine period, Edessa became the centre of intellectual life within the Syriac Orthodox Church. As such it also became the centre for the translation of Ancient Greek philosophy into Syriac, which provided a stepping stone for the subsequent translations into Arabic. When the crusades arrived, it was still important enough to tempt a side-expedition after the siege of Antioch.

Baldwin I (1060s – 2 April 1118) was the first count of Edessa from 1098 to 1100 and king of Jerusalem from 1100 to his death in 1118. He was the youngest son of Eustace II, Count of Boulogne, and Ida of Lorraine and married a Norman noblewoman, Godehilde of Tosny. He received the County of Verdun in 1096, but he soon joined the crusader army of his brother Godfrey of Bouillon and became one of the most successful commanders of the First Crusade.

While the main crusader army was marching across Asia Minor in 1097, Baldwin and the Norman Tancred launched a separate expedition against Cilicia. Tancred tried to capture Tarsus in September, but Baldwin forced him to leave it, which gave rise to an enduring conflict between them. Baldwin seized important fortresses in the lands to the west of the Euphrates with the assistance of local Armenians. Thoros of Edessa invited him to come to Edessa to fight against the Seljuks. Taking advantage of a riot against Thoros, Baldwin seized the town and established the first Crusader state on 10 March 1098. To strengthen his rule, the widowed Baldwin married an Armenian ruler's daughter (who is now known as Arda). He supplied the main crusader army with food during the siege of Antioch. He defended Edessa against Kerbogha, the governor of Mosul, for three weeks, preventing him from reaching Antioch before the crusaders captured it.

Frisian involvement in the Crusades is attested from the very beginning of the First Crusade, but their presence is only felt substantially during the Fifth Crusade. They participated in almost all the major Crusades and the Reconquista. The Frisians are almost always referred to collectively by contemporary chroniclers of the Crusades and few names of individual Frisian crusaders can be found in the historical record. They generally composed a naval force in conjunction with other larger bodies of crusaders.

The first Frisians to participate in the First Crusade were part of the army which was led to the Holy Land by Godfrey of Bouillon and they are only mentioned in passing by Fulcher of Chartres, who mentions that the Frisian language was one of the many tongues spoken by the crusaders. William of Tyre, drawing his information from Fulcher, mentions Frisians as part of the troops led by Godfrey at the Siege of Antioch in 1097–1098. According to Albert of Aix, there was also a fleet of pirates, hailing from Denmark, Frisia, and Flanders and led by Guynemer of Boulogne, who assisted Baldwin of Boulogne at Tarsus.

Stephen Henry (in French, Étienne Henri, in Old French, Estienne Henri; c. 1045 – 19 May 1102) was the count of Blois and Chartres. He led an army during the First Crusade, was at the surrender of the city of Nicaea, and directed the siege of Antioch. Returning home without fulfilling his crusader vows, Stephen joined the crusade of 1101. Making his way to Jerusalem, he fought in the Second Battle of Ramla, where he was captured and later executed.