The First Crusade (1095–1099) was the first of a number of crusades that attempted to recapture the Holy Lands, called by Pope Urban II in 1095. It started as a widespread pilgrimage in western Christendom and ended as a military expedition by Roman Catholic Europe to regain the Holy Lands taken in the Muslim conquests of the Levant (632–661), ultimately resulting in the capture of Jerusalem in 1099.
It was launched on 27 November 1095 by Pope Urban II with the primary goal of responding to an appeal from Byzantine Emperor Alexios I Komnenos, who requested that western volunteers come to his aid and help to repel the invading Seljuk Turks from Anatolia. An additional goal soon became the principal objective—the Christian reconquest of the sacred city of Jerusalem and the Holy Land and the freeing of the Eastern Christians from Muslim rule.
During the crusade, knights, peasants and serfs from many regions of Western Europe travelled over land and by sea, first to Constantinople and then on towards Jerusalem. The Crusaders arrived at Jerusalem, launched an assault on the city, and captured it in July 1099, massacring many of the city's Muslim and Jewish inhabitants. They also established the crusader states of the Kingdom of Jerusalem, the County of Tripoli, the Principality of Antioch, and the County of Edessa.
The First Crusade was followed by the Second to the Ninth Crusades. It was also the first major step towards reopening international trade in the West since the fall of the Western Roman Empire. Due to the First Crusade being largely concerned with Jerusalem, a city which had not been under Christian dominion for 461 years, and that the crusader army, on seizure of lands, had refused to honour a brokered promise before the seizure to return gained lands to the control of the Byzantine Empire, the status of the First Crusade as defensive or aggressive in nature remains unanswered and controversial. The majority view is that it had elements of both in its nature.