The First Crusade occurred between 1095 and 1099. It began with the plea from Byzantine emperor Alexius Comnenus I to the Pope in Rome and the Western nations to send him help against the encroaching Seljuk Turks. It ended when the European Crusaders captured Jerusalem.
It seems inadequate to point to one brief clarion call to action. Motives and the events that inspired those motives, mistakes, errors and grand designs must also be analyzed to reach better understanding of the WHY a thing happened.
The Near East had become united under a Muslim banner. Jerusalem had surrendered to the Arab advance in 638. By 646 Syria and Egypt were also Muslim. The Byzantine Empire, descendant of the Roman, was losing its eastern territories. Even Constantinople was besieged twice in 674 and 717.
The Byzantine forces, still strong, were able to take back many of the cities in the Levant, as Muslim rulers were as fractured as were the Europeans and Byzantines. Perhaps if they had not been distracted by political infighting within the Byzantine nobility and royal house, the Byzantines might have found common unity with the Europeans and consolidated their strength to maintain a strong presence in the Levant. In any case, they stopped short of attacking and capturing Jerusalem. That would have to wait.
Under Byzantine Emperor Basil II, the Empire had experienced a resurgence of power, almost doubling in size. Unfortunately he had left no heir, and his successors were chosen by the court bureaucrats to be only weak and pliable. The empire began to wither and weaken, exacerbated by a final religious schism between the Roman Church and the Byzantine Orthodox in 1054. The empire, once able to refuse demands from the Muslim Fatimids in Egypt, was now alone. Even the local militias that had guarded its frontiers had been disbanded.
Then the Seljuk Turks broke on the scene, moving from the east. They were nomads, used to marauding. They replaced the Abbasid caliphate in Baghdad in 1055, and by 1067 they were virtually unopposed as they looted through Armenia. Emperor Romanus Diogenes pushed them back once across the Euphrates, but instead of this garnering him support, the aristocracy instead feared his strength. Then he met the Turks at Manzikert, and his army was defeated and he was captured and humbled in 1071. In truth, the Turkish sultan had offered terms, but the Byzantine nobles had refused. Even after, their continued infighting unleashed civil war throughout the Empire. The Turks poured into Asia Minor, and instead of joining to stop them, Byzantine generals used them as mercenaries against each other. Within ten years, 30,000 square miles of Asia Minor had been lost forever.
Then Alexius Comnenus became Emperor. He watched as the Turks captured Antioch, then Edessa and most of Syria, from the Arab caliphates. The Turks captured Jerusalem in 1087, and cut off the pilgrim routes. Then the Turkish sultan died and his kingdom splintered. If ever an opportunity was ripe, this was it. But Alexius needed allies, so he wrote to the Pope in Rome in March 1095.
Before the Turks had arrived, on the whole, Christians in the Holy Land had not suffered under Muslim rule. Pilgrimages were even allowed unhampered into the Holy Land from Europe. Christians had to pay a tax, but then again, Muslims had to pay a tax wherever they lived under Byzantine control. And the Christians, no matter their particular set of beliefs, were free to worship as they wished. Many may have converted to Islam to avoid the tax, but in the East, people had long been used to exploring new ideas and finding new spiritual paths.
The idea of liberating the Holy Land was not new in 1095. An earlier Pope in Rome had already heard about the Turkish advance by 1074, and he had personally proposed to lead a force of 50,000 volunteers to liberate eastern Christians then. That attempt was halted by troubles in Europe affecting the papacy and its supporters, but surely the Emperor’s message did not cause spontaneous inspiration twenty years later.
Did Alexius himself mean to start a Crusade? Two Latin chroniclers wrote that he sought help to defend the Byzantine church as a whole. But a Greek chronicler reported that all the Emperor sought was aid to drive the Seljuks out of Asia Minor and give Byzantium a chance to strengthen its frontiers. By the Council of Clermont in November, several months after Alexius’ message reached Pope Urban, and Urban made his speech at Clermont, the Pope had decided that the liberation of Jerusalem and the Holy Land was to be the true purpose of any Christian army.
Brownworth, L. (2009). Lost to the West: The Forgotten Byzantine Empire that Rescued Western Civilization. Crown Publishers.
Charanis, P. (1949). A Greek Source on the Origin of the First Crusade. Medieval Academy of America.
Paine, M. (2009). The Crusades: History and Myths Revealed. Falls River Press