The Crusades were a series of religious wars sanctioned by the Latin Church in the medieval period, especially the campaigns in the Eastern Mediterranean with the aim of recovering the Holy Land from Islamic rule The most Popular and successful crusade was the first crusade.
Crusade #1: The First Crusade arose after a call to arms in a 1095 sermon by Pope Urban II. Urban urged military support for the Byzantine Empire and its Emperor, Alexios I, who needed reinforcements for his conflict with westward migrating Turks in Anatolia. One of Urban's stated aims was to guarantee pilgrims access to the holy sites in the Eastern Mediterranean that were under Muslim control. Volunteers became Crusaders by taking a public vow and receiving plenary indulgences from the church. Some were hoping for apotheosis at Jerusalem, or forgiveness from God for all their sins. Others participated to satisfy feudal obligations, gain glory and honor, or find opportunities for economic and political
Crusade #2: The Second Crusade was announced by Pope Eugene III, and was the first of the crusades to be led by European kings, namely Louis VII of France and Conrad III of Germany, with help from some other European nobles. The armies of the two kings marched separately across Europe. After crossing Byzantine territory into Anatolia, both armies were separately defeated by the Seljuk Turks. The only Christian success of the Second Crusade came to a combined force of 13,000 Flemish, Frisian, Norman, English, Scottish, and German crusaders in 1147. Traveling from England, by ship, to the Holy Land, the army stopped and helped the smaller (7,000) Portuguese army in the capture of Lisbon, expelling its Moorish occupants.
Crusade #3: The elderly Holy Roman EmperorFrederick I Barbarossa responded to the call immediately. He took up the Cross at Mainz Cathedral on 27 March 1188 and was the first to set out for the Holy Land in May 1189 with an army of about 100,000 men, including 20,000 knights.An army of 2,000 men from the Hungarian prince Géza, the younger brother of the king Béla III of Hungary, also went with Barbarossa to the Holy Land. This is also the Crusade where King Richard the Lion-Hearted and King Philip the 2nd went.
Crusade #4: Innocent III also began preaching what became the Fourth Crusade in 1200, primarily in France, but also in England and Germany. After gathering in Venice, the crusade was used by Doge Enrico Dandolo and Philip of Swabia to further their secular ambitions. Dandolo's aim was to expand Venice's power in the Eastern Mediterranean, and Philip intended to restore his exiled nephew, Alexios IV Angelos, to the throne of Byzantium. The Crusaders were unable to pay the Venetians for a fleet when too few knights arrived in Venice, so they agreed to divert to Constantinople and share what could be looted as payment. As collateral the crusaders seized the Christian city of Zara; Innocent was appalled and excommunicated them. They also conquered Constantinople twice, after the initial success in taking the city, the original purpose of the campaign was defeated by the assassination of Alexios IV Angelos. In response, the Crusaders captured the Constantinople again and this time sacked it, pillaging churches and killing many citizens. The Fourth Crusade never came within 1,000 miles of its objective of Jerusalem
