The Crusades are a series of military conflicts of a religious character waged by much of Christian Europe against external and internal threats; there is also rioting.

Crusades are fought mainly against Muslims, though campaigns are also directed against pagan Slavs, Jews, Russian and Greek Orthodox Christians, Mongols, Cathars, Hussites, and political enemies of the popes.

Crusaders take vows and ae granted an indulgence for past sins.

The Crusades originally have the goal of recapturing Jerusalem and the Holy Land from Muslim rule and are originally launched in response to a call from the Eastern Orthodox Byzantine Empire for help against the expansion of the Muslim Seljuk Turks into Anatolia.

The term is also used to describe contemporaneous and subsequent campaigns conducted through to the 16th century in territories outside the Levant, usually against pagans, heretics, and peoples under the ban of excommunication for a mixture of religious, economic, and political reasons.

Rivalries among both Christian and Muslim powers lead also to alliances between religious factions against their opponents, such as the Christian alliance with the Sultanate of Rum during the Fifth Crusade.The Crusades are to have far-reaching political, economic, and social impacts, some of which have lasted into contemporary times.

Because of internal conflicts among Christian kingdoms and political powers, some of the crusade expeditions are diverted from their original aim, such as the Fourth Crusade, which results in the sack of Christian Constantinople and the partition of the Byzantine Empire between Venice and the Crusaders.

The Sixth Crusade is the first crusade to set sail without the official blessing of the Pope.

The Seventh, Eighth and Ninth Crusades result in Mamluk and Hafsid victories, as the Ninth Crusade marks the end of the Crusades in the Middle East.The First Crusade is launched in 1096 by Pope Urban II with the dual goals of conquering the sacred city of Jerusalem and the Holy Land and freeing the Eastern Christians from Islamic rule.

What starts as an appeal by Byzantine Emperor Alexius I Comnenus for western mercenaries to fight the Seljuk Turks in Anatolia quickly turns into a wholesale Western migration and conquest of territory outside of Europe.

Both knights and peasants from many nations of Western Europe travel over land and by sea towards Jerusalem and capture the city in July 1099, establishing the Kingdom of Jerusalem and other Crusader states.

Although these gains last for less than two hundred years, the First Crusade is a major turning point in the expansion of Western power, as well as the first major step towards reopening international trade in the West since the fall of the Western Roman Empire.