The Fifth Crusade (1213–1221) was an attempt to reacquire Jerusalem and the rest of the Holy Land by first conquering the powerful Ayyubid state in Egypt.

Pope Innocent III and his successor Pope Honorius III organized crusading armies led by King Andrew II of Hungary and Duke Leopold VI of Austria, and a foray against Jerusalem ultimately left the city in Muslim hands. Later in 1218, a German army led by Oliver of Cologne, and a mixed army of Dutch, Flemish and Frisian soldiers led by William I, Count of Holland joined the crusade. In order to attack Damietta in Egypt, they allied in Anatolia with the Seljuk Sultanate of Rûm which attacked the Ayyubids in Syria in an attempt to free the Crusaders from fighting on two fronts.

After occupying the port of Damietta, the Crusaders marched south towards Cairo in July 1221, but were turned back after their dwindling supplies led to a forced retreat. A nighttime attack by Sultan Al-Kamil resulted in a great number of crusader losses, and eventually in the surrender of the army. Al-Kamil agreed to an eight-year peace agreement with Europe.

Walther von der Vogelweide (c. 1170 – c. 1230) is the most celebrated of the Middle High German lyric poets.

For all his fame, Walther's name is not found in contemporary records, with the exception of a solitary mention in the travelling accounts of Bishop Wolfger of Erla of the Passau diocese: "Walthero cantori de Vogelweide pro pellicio v solidos longos"--"To Walther the singer of the Vogelweide five shillings for a fur coat." The main sources of information about him are his own poems and occasional references by contemporary Minnesingers. He was a knight, but probably not a wealthy or landed one. His whole name (in English "Sir Walter of the Bird-Field") suggests that he didn't have a grant of land, since "bird-field" is a general geographic surname like "forest", "hill" or "rivers", not the name of a specific place. He probably was knighted for military bravery and, like a Knight Bachelor of England or samurai in Japan, was initially a retainer in a wealthy, noble household and had rooms in that castle before beginning his travels.

Rodney Stark is an American sociologist of religion. He grew up in Jamestown, North Dakota in a Lutheran family. He spent time in the U.S. Army and worked as a journalist before pursuing graduate studies at The University of California, Berkeley. After teaching at the University of Washington for 32 years, Stark moved to Baylor University in 2004, where he is co-director of the Institute for Studies of Religion. He is an advocate of the application of the Rational choice theory in the sociology of religion, which he calls the theory of religious economy.

During the late 1970s and 1980s, Stark worked with William Sims Bainbridge on the Stark-Bainbridge theory of religion, and co-wrote the books The Future of Religion (1985) and A Theory of Religion (1987) with Bainbridge. Nowadays their theory, which aims to explain religious involvement in terms of rewards and compensators, is seen as a precursor of the more explicit recourse to economic principles in the study of religion as later developed by Laurence Iannaccone and others.