Overview
The title of Advocatus Sancti Sepulchri, or Advocate of the Holy Sepulchre, has been ascribed to Godfrey of Bouillon in his role as the first Latin ruler of Jerusalem. In the aftermath of the First Crusade, there was disagreement among the clergy and secular leaders as the leadership of the Kingdom of Jerusalem. There was opposition to the naming of a king over the Holy City and the wearing of a crown in the city where Christ suffered with a crown of thorns. The original sources differ on the actual title assumed by Godfrey. However, it is generally accepted by most modern historians that, once Godfrey was selected to be leader, he declined to be crowned king instead taking the titles of prince (princeps) and advocate or defender of the Holy Sepulchre (advocatus Sancti Sepulchri).
The First Crusade
At the beginning of eleventh century, the city of Jerusalem had been under Islamic rule for almost five centuries. Then a series of events began to limit the access of Christian pilgrims to the Holy City and encroach on the Byzantine Empire. The First Crusade, first called for in 1095, sought to restore Jerusalem to Christian control. Begun as a joint effort of Western Europe and Constantinople, the final determination was that newly captured territory would be formed as its own kingdom.
Background
Among the earliest of the faithful to travel to the Holy Land was Saint Helena, mother of Constantine the Great, whose pilgrimage began in 326 AD. According to tradition, her travels led to the discovery of the True Cross. On the site of discovery, her son Constantine ordered the building of the Church of the Holy Sepulchre. Pilgrimages to the Holy Land became a tradition of devout Christians and continued even after the conquest of these lands by the Muslims following the Siege of Jerusalem in the 7th century.
A major disruption to these pilgrimages when the Fatimid caliph al-Hakim ordered the destruction of the Church of the Holy Sepulchre in Jerusalem on 28 September 1009. The subsequent persecution of Christians and destruction of their churches lasted for more than a decade. After the Battle of Manzikert in 1071, the Seljuk Turks overcame the Byzantines and invaded Asia Minor. Shortly thereafter, the Seljuks captured Jerusalem from the Fatimides, and his fellow tribesmen systematically disrupted Christian pilgrimage routes. This would lead to the First Crusade.
From Wikipedia (CC BY-SA 4.0).